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ODBC(3)		      User Contributed Perl Documentation	       ODBC(3)

NAME
       DBD::ODBC - ODBC Driver for DBI

VERSION
       This documentation refers to DBD::ODBC version 1.33.

SYNOPSIS
	 use DBI;

	 $dbh = DBI->connect('dbi:ODBC:DSN', 'user', 'password');

       See DBI for more information.

DESCRIPTION
   Change log and FAQs
       Please note that the change log has been moved to DBD::ODBC::Changes.
       To access this documentation, use "perldoc DBD::ODBC::Changes".

       The FAQs have also moved to DBD::ODBC::FAQ.pm. To access the FAQs use
       "perldoc DBD::ODBC::FAQ".

   Important note about the tests
       Please note that some tests may fail or report they are unsupported on
       this platform.  Notably Oracle's ODBC driver will fail the "advanced"
       binding tests in t/08bind2.t.  These tests run perfectly under SQL
       Server 2000. This is normal and expected.  Until Oracle fixes their
       drivers to do the right thing from an ODBC perspective, it's going to
       be tough to fix the issue.  The workaround for Oracle is to bind date
       types with SQL_TIMESTAMP.  Also note that some tests may be skipped,
       such as t/09multi.t, if your driver doesn't seem to support returning
       multiple result sets.  This is normal.

   Version Control
       DBD::ODBC source code is under version control at svn.perl.org.	If you
       would like to use the "bleeding" edge version, you can get the latest
       from svn.perl.org via Subversion version control.  Note there is no
       guarantee that this version is any different than what you get from the
       tarball from CPAN, but it might be :)

       You may read about Subversion at <http://subversion.tigris.org>

       You can get a subversion client from there and check dbd-odbc out via:

	  svn checkout http://svn.perl.org/modules/dbd-odbc/trunk <your directory name here>

       Which will pull all the files from the subversion trunk to your
       specified directory. If you want to see what has changed since the last
       release of DBD::ODBC read the Changes file or use "svn log" to get a
       list of checked in changes.

   Contributing
       There are seven main ways you may help with the development and
       maintenance of this module:

       Submitting patches
	   Please use Subversion (see above) to get the latest version of
	   DBD::ODBC from the trunk and submit any patches against that.

	   Please, before submitting a patch:

	      svn update
	      <try and included a test which demonstrates the fix/change working>
	      <test your patch>
	      svn diff > describe_my_diffs.patch

	   and send the resulting file to me and cc the dbi-users@perl.org
	   mailing list (if you are not a member - why not!).

       Reporting installs
	   Install CPAN::Reporter and report you installations. This is easy
	   to do - see "CPAN Testers Reporting".

       Report bugs
	   If you find what you believe is a bug then enter it into the
	   <http://rt.cpan.org/Dist/Display.html?Name=DBD-ODBC> system. Where
	   possible include code which reproduces the problem including any
	   schema required and the versions of software you are using.

	   If you are unsure whether you have found a bug report it anyway or
	   post it to the dbi-users mailing list.

       pod comments and corrections
	   If you find inaccuracies in the DBD::ODBC pod or have a comment
	   which you think should be added then go to <http://annocpan.org>
	   and submit them there. I get an email for every comment added and
	   will review each one and apply any changes to the documentation.

       Review DBD::ODBC
	   Add your review of DBD::ODBC on <http://cpanratings.perl.org>.

	   If you are a member on ohloh then add your review or register your
	   use of DBD::ODBC at <http://www.ohloh.net/projects/perl_dbd_odbc>.

       submit test cases
	   Most DBDs are built against a single client library for the
	   database.

	   Unlike other DBDs, DBD::ODBC works with many different ODBC
	   drivers.  Although they all should be written with regard to the
	   ODBC specification drivers have bugs and in some places the
	   specification is open to interpretation. As a result, when changes
	   are applied to DBD::ODBC it is very easy to break something in one
	   ODBC driver.

	   What helps enormously to identify problems in the many combinations
	   of DBD::ODBC and ODBC drivers is a large test suite. I would
	   greatly appreciate any test cases and in particular any new test
	   cases for databases other than MS SQL Server.

       Test DBD::ODBC
	   I have a lot of problems deciding when to move a development
	   release to an official release since I get few test reports for
	   development releases. What often happens is I call for testers on
	   various lists, get a few and then get inundated with requests to do
	   an official release. Then I do an official release and loads of rts
	   appear out of nowhere and the cycle starts again.

	   DBD::ODBC by its very nature works with many ODBC Drivers and it is
	   impossible for me to have and test them all (this differs from
	   other DBDs). If you depend on DBD::ODBC you should be interested in
	   new releases and if you send me your email address suggesting you
	   are prepared to be part of the DBD::ODBC testing network I will
	   credit you in the Changes file and perhaps the main DBD::ODBC file.

   DBI attribute handling
       If a DBI defined attribute is not mentioned here it behaves as per the
       DBI specification.

       ReadOnly (boolean)

       DBI documents the "ReadOnly" attribute as being settleable and
       retrievable on connection and statement handles. In ODBC setting
       ReadOnly to true causes the connection attribute "SQL_ATTR_ACCESS_MODE"
       to be set to "SQL_MODE_READ_ONLY" and setting it to false will set the
       access mode to "SQL_MODE_READ_WRITE" (which is the default in ODBC).

       Note: There is no equivalent of setting ReadOnly on a statement handle
       in ODBC.

       Note: See ODBC documentation on "SQL_ATTR_ACCESS_MODE" as setting it to
       "SQL_MODE_READ_ONLY" does not prevent your script from running updates
       or deletes; it is simply a hint to the driver/database that you won't
       being doing updates.

       This attribute requires DBI version 1.55 or better.

   Private attributes common to connection and statement handles
       odbc_ignore_named_placeholders

       Use this if you have special needs (such as Oracle triggers, etc) where
       :new or :name mean something special and are not just place holder
       names. You must then use ? for binding parameters.  Example:

	$dbh->{odbc_ignore_named_placeholders} = 1;
	$dbh->do("create trigger foo as if :new.x <> :old.x then ... etc");

       Without this, DBD::ODBC will think :new and :old are placeholders for
       binding and get confused.

       odbc_default_bind_type

       This value defaults to 0.

       Older versions of DBD::ODBC assumed that the parameter binding type was
       12 ("SQL_VARCHAR").  Newer versions always attempt to call
       "SQLDescribeParam" to find the parameter types but if
       "SQLDescribeParam" is unavailable DBD::ODBC falls back to a default
       bind type. The internal default bind type is "SQL_VARCHAR" (for non-
       unicode build) and "SQL_WVARCHAR" (for a unicode build). If you set
       "odbc_default_bind_type" to a value other than 0 you override the
       internal default.

       N.B If you call the "bind_param" method with a SQL type this overrides
       everything else above.

       odbc_force_bind_type

       This value defaults to 0.

       If set to anything other than 0 this will force bound parameters to be
       bound as this type and "SQLDescribeParam" will not be used.

       Older versions of DBD::ODBC assumed the parameter binding type was 12
       ("SQL_VARCHAR") and newer versions always attempt to call
       "SQLDescribeParam" to find the parameter types. If your driver supports
       "SQLDescribeParam" and it succeeds it may still fail to describe the
       parameters accurately (MS SQL Server sometimes does this with some SQL
       like select myfunc(?)  where 1 = 1). Setting "odbc_force_bind_type" to
       "SQL_VARCHAR" will force DBD::ODBC to bind all the parameters as
       "SQL_VARCHAR" and ignore SQLDescribeParam.

       Bare in mind that if you are inserting unicode data you probably want
       to use "SQL_WVARCHAR" and not "SQL_VARCHAR".

       As this attribute was created to work around buggy ODBC Drivers which
       support SQLDescribeParam but describe the parameters incorrectly you
       are probably better specifying the bind type on the "bind_param" call
       on a per statement level rather than blindly setting
       "odbc_force_bind_type" across a whole connection.

       N.B If you call the "bind_param" method with a SQL type this overrides
       everything else above.

       odbc_force_rebind

       This is to handle special cases, especially when using multiple result
       sets.  Set this before execute to "force" DBD::ODBC to re-obtain the
       result set's number of columns and column types for each execute.
       Especially useful for calling stored procedures which may return
       different result sets each execute.  The only performance penalty is
       during execute(), but I didn't want to incur that penalty for all
       circumstances.  It is probably fairly rare that this occurs.  This
       attribute will be automatically set when multiple result sets are
       triggered.  Most people shouldn't have to worry about this.

       odbc_async_exec

       Allow asynchronous execution of queries.	 This causes a spin-loop (with
       a small "sleep") until the ODBC API being called is complete (i.e.,
       while the ODBC API returns "SQL_STILL_EXECUTING").  This is useful,
       however, if you want the error handling and asynchronous messages (see
       the "odbc_err_handler" and t/20SQLServer.t for an example of this).

       odbc_query_timeout

       This allows you to change the ODBC query timeout (the ODBC statement
       attribute "SQL_ATTR_QUERY_TIMEOUT"). ODBC defines the query time out as
       the number of seconds to wait for a SQL statement to execute before
       returning to the application. A value of 0 (the default) means there is
       no time out. Do not confuse this with the ODBC attributes
       "SQL_ATTR_LOGIN_TIMEOUT" and "SQL_ATTR_CONNECTION_TIMEOUT". Add

	 { odbc_query_timeout => 30 }

       to your connect, set on the "dbh" before creating a statement or
       explicitly set it on your statement handle. The odbc_query_timeout on a
       statement is inherited from the parent connection.

       Note that internally DBD::ODBC only sets the query timeout if you set
       it explicitly and the default of 0 (no time out) is implemented by the
       ODBC driver and not DBD::ODBC.

       Note that some ODBC drivers implement a maximum query timeout value and
       will limit timeouts set above their maximum. You may see a warning if
       your time out is capped by the driver but there is currently no way to
       retrieve the capped value back from the driver.

       Note that some drivers may not support this attribute.

       See t/20SqlServer.t for an example.

       odbc_putdata_start

       "odbc_putdata_start" defines the size at which DBD::ODBC uses
       "SQLPutData" and "SQLParamData" to send larger objects to the database
       instead of simply binding them as normal with "SQLBindParameter". It is
       mostly a placeholder for future changes allowing chunks of data to be
       sent to the database and there is little reason for anyone to change it
       currently.

       The default for odbc_putdata_start is 32768 because this value was
       hard-coded in DBD::ODBC until 1.16_1.

       odbc_column_display_size

       If you ODBC driver does not support the SQL_COLUMN_DISPLAY_SIZE and
       SQL_COLUMN_LENGTH attributes to SQLColAtrributes then DBD::ODBC does
       not know how big the column might be. odbc_column_display_size sets the
       default value for the column size when retrieving column data where the
       size cannot be determined.

       The default for odbc_column_display_size is 2001 because this value was
       hard-coded in DBD::ODBC until 1.17_3.

       odbc_utf8_on

       Set this flag to treat all strings returned from the ODBC driver
       (except columns described as SQL_BINARY or SQL_TIMESTAMP and its
       variations) as UTF-8 encoded.  Some ODBC drivers (like Aster and maybe
       PostgreSQL) return UTF-8 encoded data but do not support the SQLxxxW
       unicode API. Enabling this flag will cause DBD::ODBC to treat driver
       returned data as UTF-8 encoded and it will be marked as such in Perl.

       Do not confuse this with DBD::ODBC's unicode support. The
       "odbc_utf8_on" attribute only applies to non-unicode enabled builds of
       DBD::ODBC.

       odbc_old_unicode

       Defaults to off. If set to true returns DBD::ODBC to the old unicode
       behavior in 1.29 and earlier. You can also set this on the prepare
       method.

       By default DBD::ODBC now binds all char columns as SQL_WCHARs meaning
       the driver is asked to return the bound data as wide (Unicode)
       characters encoded in UCS2. So long as the driver supports the ODBC
       Unicode API properly this should mean you get your data back correctly
       in Perl even if it is in a character set (codepage) different from the
       one you are working in.

       However, if you wrote code using DBD::ODBC 1.29 or earlier and knew
       DBD::ODBC bound varchar/longvarchar columns as SQL_CHARs and decoded
       them yourself the new behaviour will adversely affect you (sorry). To
       revret to the old behaviour set odbc_old_unicode to true.

       You can also set this attribute in the attributes passed to the prepare
       method.

       See the stackoverflow question at
       <http://stackoverflow.com/questions/5912082>, the RT at
       <http://rt.cpan.org/Public/Bug/Display.html?id=67994> and lastly a
       small discussion on dbi-dev at
       <http://www.nntp.perl.org/group/perl.dbi.dev/2011/05/msg6559.html>.

       odbc_describe_parameters

       Defaults to on. When set this allows DBD::ODBC to call SQLDescribeParam
       (if the driver supports it) to retrieve information about any
       parameters.

       When off/false DBD::ODBC will not call SQLDescribeParam and defaults to
       binding parameters as SQL_CHAR/SQL_WCHAR depending on the build type.

       You do not have to disable odbc_describe_parameters just because your
       driver does not support SQLDescribeParam as DBD::ODBC will work this
       out at the start via SQLGetFunctions.

       Note: disabling odbc_describe_parameters when your driver does support
       SQLDescribeParam may prevent DBD::ODBC binding parameters for some
       column types properly.

       You can also set this attribute in the attributes passed to the prepare
       method.

       This attribute was added so someone moving from freeTDS (a driver which
       does not support SQLDescribeParam) to a driver which does support
       SQLDescribeParam could do so without changing any Perl. The situation
       was very specific since dates were being bound as dates when
       SQLDescribeParam was called and chars without and the data format was
       not a supported date format.

   Private connection attributes
       odbc_err_handler

       NOTE: You might want to look at DBI's error handler before using the
       one in DBD::ODBC however, there are subtle differences. DBD::ODBC's
       odbc_err_handler is called for error and informational diagnostics
       i.e., it is called when an ODBC call fails the SQL_SUCCEEDED macro
       which means the ODBC call returned SQL_ERROR (-1) or
       SQL_SUCCESS_WITH_INFO \fIs0(1).

       Allow error and informational diagnostics to be handled by the
       application.  A call-back function supplied by the application to
       handle or ignore messages.

       The callback function receives four parameters: state (string), error
       (string), native error code (number) and the status returned from the
       last ODBC API. The fourth argument was added in 1.30_7.

       If the error handler returns 0, the error is ignored, otherwise the
       error is passed through the normal DBI error handling. Note, if the
       status is SQL_SUCCESS_WITH_INFO this will not reach the DBI error
       handler as it is not an error.

       This can also be used for procedures under MS SQL Server (Sybase too,
       probably) to obtain messages from system procedures such as DBCC.
       Check t/20SQLServer.t and t/10handler.t.

	 $dbh->{RaiseError} = 1;
	 sub err_handler {
	    ($state, $msg, $native, $rc, $status) = @_;
	    if ($state = '12345')
		return 0; # ignore this error
	    else
		return 1; # propagate error
	 }
	 $dbh->{odbc_err_handler} = \&err_handler;
	 # do something to cause an error
	 $dbh->{odbc_err_handler} = undef; # cancel the handler

       odbc_SQL_ROWSET_SIZE

       Setting odbc_SQL_ROWSET_SIZE results in a call to SQLSetConnectAttr to
       set the ODBC SQL_ROWSET_SIZE \fIs0(9) attribute to whatever value you
       set odbc_SQL_ROWSET_SIZE to.

       The ODBC default for SQL_ROWSET_SIZE is 1.

       Usually MS SQL Server does not support multiple active statements (MAS)
       i.e., you cannot have 2 or more outstanding selects.  You can set
       odbc_SQL_ROWSET_SIZE to 2 to persuade MS SQL Server to support multiple
       active statements.

       Setting SQL_ROWSET_SIZE usually only affects calls to SQLExtendedFetch
       but does allow MAS and as DBD::ODBC does not use SQLExtendedFetch there
       should be no ill effects to DBD::ODBC.

       Be careful with this attribute as once set to anything larger than 1
       (the default) you must retrieve all result-sets before the statement
       handle goes out of scope or you can upset the TDS protocol and this can
       result in a hang. With DBI this is unlikely as DBI warns when a
       statement goes out of scope with outstanding results.

       NOTE: if you get an error saying "[Microsoft][ODBC SQL Server
       Driver]Invalid attribute/option identifier (SQL-HY092)" when you set
       odbc_SQL_ROWSET_SIZE in the connect method you need to either a)
       upgrade to DBI 1.616 or above b) set odbc_SQL_ROWSET_SIZE after
       connect.

       In versions of SQL Server 2005 and later see "Multiple Active
       Statements (MAS)" in the DBD::ODBC::FAQ instead of using this
       attribute.

       Thanks to Andrew Brown for the original patch.

       DBD developer note: Here lies a bag of worms. Firstly, SQL_ROWSET_SIZE
       is an ODBC 2 attribute and is usally a statement attribute not a
       connection attribute. However, in ODBC 2.0 you could set statement
       attributes on a connection handle and it acted as a default for all
       subsequent statement handles created under that connection handle. If
       you are using ODBC 3 the driver manager continues to map this call but
       the ODBC Driver needs to act on it (the MS SQL Server driver still
       appears to but some other ODBC drivers for MS SQL Server do not).
       Secondly, somewhere a long the line MS decided it was no longer valid
       to retrieve the SQL_ROWSET_SIZE attribute from a connection handle in
       an ODBC 3 application (which DBD::ODBC now is). In itself, this would
       not be a problem except for a minor bug in DBI which until release
       1.616 mistakenly issued a FETCH on any attribute mentioned in the
       connect method call. As a result, it you use a DBI prior to 1.616 and
       attempt to set odbc_SQL_ROWSET_SIZE in the connect method call, DBI
       issues a FETCH on odbc_SQL_ROWSET_SIZE and the driver manager throws it
       out as an invalid attribute thus resulting in an error. The only way
       around this (other than upgrading DBI) is to set odbc_SQL_ROWSET_SIZE
       AFTER the call to connect. Thirdly, MS withdrew the SQLROWSETSIZE macro
       from the sql header files in MDAC 2.7 for 64 bit platforms i.e.,
       SQLROWSETSIZE is not defined on 64 bit platforms from MDAC 2.7 as it is
       in a "#ifdef win32" (see
       http://msdn.microsoft.com/en-us/library/ms716287%28v=vs.85%29.aspx).
       Setting SQL_ROWSET_SIZE still seems to take effect on 64 bit platforms
       but you can no longer retrieve its value from a connection handle
       (hence the issue above with DBI redundant FETCH).

       odbc_exec_direct

       Force DBD::ODBC to use "SQLExecDirect" instead of
       "SQLPrepare"/"SQLExecute".

       There are drivers that only support "SQLExecDirect" and the DBD::ODBC
       do() override does not allow returning result sets.  Therefore, the way
       to do this now is to set the attribute odbc_exec_direct.

       NOTE: You may also want to use this option if you are creating
       temporary objects (e.g., tables) in MS SQL Server and for some reason
       cannot use the "do" method. see
       <http://technet.microsoft.com/en-US/library/ms131667.aspx> which says
       Prepared statements cannot be used to create temporary objects on SQL
       Server 2000 or later.... Without odbc_exec_direct, the temporary object
       will disappear before you can use it.

       There are currently two ways to get this:

	   $dbh->prepare($sql, { odbc_exec_direct => 1});

       and

	   $dbh->{odbc_exec_direct} = 1;

       NOTE: Even if you build DBD::ODBC with unicode support you can still
       not pass unicode strings to the prepare method if you also set
       odbc_exec_direct. This is a restriction in this attribute which is
       unavoidable.

       odbc_SQL_DRIVER_ODBC_VER

       This, while available via get_info() is captured here.  I may get rid
       of this as I only used it for debugging purposes.

       odbc_cursortype

       This allows multiple concurrent statements on SQL*Server.  In your
       connect, add

	 { odbc_cursortype => 2 }.

       If you are using DBI > 1.41, you should also be able to use

	{ odbc_cursortype => DBI::SQL_CURSOR_DYNAMIC }

       instead.	 For example:

	   my $dbh = DBI->connect("dbi:ODBC:$DSN", $user, $pass,
			 { RaiseError => 1, odbc_cursortype => 2});
	   my $sth = $dbh->prepare("one statement");
	   my $sth2 = $dbh->prepare("two statement");
	   $sth->execute;
	   my @row;
	   while (@row = $sth->fetchrow_array) {
	      $sth2->execute($row[0]);
	   }

       See t/20SqlServer.t for an example.

       odbc_has_unicode

       A read-only attribute signifying whether DBD::ODBC was built with the C
       macro WITH_UNICODE or not. A value of 1 indicates DBD::ODBC was built
       with WITH_UNICODE else the value returned is 0.

       Building WITH_UNICODE affects columns and parameters which are
       SQL_C_WCHAR, SQL_WCHAR, SQL_WVARCHAR, and SQL_WLONGVARCHAR, SQL, the
       connect method and a lot more. See "Unicode".

       When odbc_has_unicode is 1, DBD::ODBC will:

       bind columns the database declares as wide characters as SQL_Wxxx
	   This means that UNICODE data stored in these columns will be
	   returned to Perl in UTF-8 and with the UTF8 flag set.

       bind parameters the database declares as wide characters as SQL_Wxxx
	   Parameters bound where the database declares the parameter as being
	   a wide character (or where the parameter type is explicitly set to
	   a wide type - SQL_Wxxx) can be UTF8 in Perl and will be mapped to
	   UTF16 before passing to the driver.

       SQL SQL passed to the "prepare" or "do" methods which has the UTF8 flag
	   set will be converted to UTF16 before being passed to the ODBC APIs
	   "SQLPrepare" or "SQLExecDirect".

       connection strings
	   Connection strings passed to the "connect" method will be converted
	   to UTF16 before being passed to the ODBC API "SQLDriverConnectW".
	   This happens irrespective of whether the UTF8 flag is set on the
	   perl connect strings because unixODBC requires an application to
	   call SQLDriverConnectW to indicate it will be calling the wide ODBC
	   APIs.

       NOTE: You will need at least Perl 5.8.1 to use UNICODE with DBD::ODBC.

       NOTE: Binding of unicode output parameters is coded but untested.

       NOTE: When building DBD::ODBC on Windows ($^O eq 'MSWin32') the
       WITH_UNICODE macro is automatically added. To disable specify -nou as
       an argument to Makefile.PL (e.g. "perl Makefile.PL -nou"). On non-
       Windows platforms the WITH_UNICODE macro is not enabled by default and
       to enable you need to specify the -u argument to Makefile.PL. Please
       bare in mind that some ODBC drivers do not support SQL_Wxxx columns or
       parameters.

       NOTE: Unicode support on Windows 64 bit platforms is currently
       untested.  Let me know how you get on with it.

       UNICODE support in ODBC Drivers differs considerably. Please read the
       README.unicode file for further details.

       odbc_out_connect_string

       After calling the connect method this will be the ODBC driver's out
       connection string - see documentation on SQLDriverConnect.

       odbc_version

       This was added prior to the move to ODBC 3.x to allow the caller to
       "force" ODBC 3.0 compatibility.	It's probably not as useful now, but
       it allowed get_info and get_type_info to return correct/updated
       information that ODBC 2.x didn't permit/provide.	 Since DBD::ODBC is
       now 3.x, this can be used to force 2.x behavior via something like: my

	 $dbh = DBI->connect("dbi:ODBC:$DSN", $user, $pass,
			     { odbc_version =>2});

       odbc_driver_complete

       This attribute was added to DBD::ODBC in 1.32_2.

       odbc_driver_complete is only relevant to the Windows operating system
       and will be ignored on other platforms. It is off by default.

       When set to a true value DBD::ODBC attempts to obtain a window handle
       and calls SQLDriverConnect with the SQL_DRIVER_COMPLETE attribute
       instead of the normal SQL_DRIVER_NOPROMPT option. What this means is
       that if the connection string does not describe sufficient attributes
       to enable the ODBC driver manager to connect to a data source it will
       throw a dialogue allowing you to input the remaining attributes. Once
       you ok that dialogue the ODBC Driver Manager will continue as if you
       specified those attributes in the connection string. Once the
       connection is complete you may want to look at the
       odbc_out_connect_string attribute to obtain a connection string you can
       use in the future to pass into the connect method without prompting.

       As a window handle is passed to SQLDriverConnect it also means the ODBC
       driver may throw a dialogue e.g., if your password has expired the MS
       SQL Server driver will often prompt for a new one.

       An example is:

	 my $h = DBI->connect('dbi:ODBC:DRIVER={SQL Server}', "username", "password",
			      {odbc_driver_complete => 1});

       As this only provides the driver and further attributes are required a
       dialogue will be thrown allowing you to specify the SQL Server to
       connect to and possibly other attributes.

   Private statement methods
       odbc_lob_read

	 $chrs_or_bytes_read = $sth->lob_read($column_no, \$lob, $length, \%attr);

       Reads $length bytes from the lob at column $column_no returning the lob
       into $lob and the number of bytes or characters read into
       $chrs_or_bytes_read. If an error occurs undef will be returned.	When
       there is no more data to be read 0 is returned.

       NOTE: This is currently an experimental method and may change in the
       future e.g., it may support automatic concatenation of the lob parts
       onto the end of the $lob with the addition of an extra flag or
       destination offset as in DBI's undocumented blob_read.

       The type the lob is retrieved as may be overriden in %attr using "TYPE
       => sql_type". %attr is optional and if omitted defaults to SQL_C_BINARY
       for binary columns and SQL_C_CHAR/SQL_C_WCHAR for other column types
       depending on whether DBD::ODBC is built with unicode support.
       $chrs_or_bytes_read will by the bytes read when the column types
       SQL_C_CHAR or SQL_C_BINARY are used and characters read if the column
       type is SQL_C_WCHAR.

       When built with unicode support $length specifes the amount of buffer
       space to be used when retrieving the lob data but as it is returned as
       SQLWCHAR characters this means you at most retrieve "$length/2"
       characters. When those retrieved characters are encoded in UTF-8 for
       Perl, the $lob scalar may need to be larger than $length so DBD::ODBC
       grows it appropriately.

       You can retrieve a lob in chunks like this:

	 $sth->bind_col($column, undef, {TreatAsLOB=>1});
	 while(my $retrieved = $sth->odbc_lob_read($column, \my $data, $length)) {
	     print "retrieved=$retrieved lob_data=$data\n";
	 }

       NOTE: to retrieve a lob like this you must first bind the lob column
       specifying BindAsLOB or DBD::ODBC will 1) bind the column as normal and
       it will be subject to LongReadLen and b) fail odbc_lob_read.

       NOTE: Some database engines and ODBC drivers do not allow you to
       retrieve columns out of order (e.g., MS SQL Server unless you are using
       cursors).  In those cases you must ensure the lob retrieved is the last
       (or only) column in your select list.

       NOTE: You can retrieve only part of a lob but you will probably have to
       call finish on the statement handle before you do anything else with
       that statement.

       NOTE: If your select contains multiple lobs you cannot read part of the
       first lob, the second lob then return to the first lob. You must read
       all lobs in order and completely or read part of a lob and then do no
       further calls to odbc_lob_read.

   Private statement attributes
       odbc_more_results

       Use this attribute to determine if there are more result sets
       available.  SQL Server supports this feature.  Use this as follows:

	 do {
	    my @row;
	    while (@row = $sth->fetchrow_array()) {
	       # do stuff here
	    }
	 } while ($sth->{odbc_more_results});

       Note that with multiple result sets and output parameters (i.e,. using
       bind_param_inout), don't expect output parameters to be bound until ALL
       result sets have been retrieved.

   Private DBD::ODBC Functions
       You use DBD::ODBC private functions like this:

	 $dbh->func(arg, private_function_name, @args);

       GetInfo

       This private function is now superceded by DBI's get_info method.

       This function maps to the ODBC SQLGetInfo call and the argument should
       be a valid ODBC information type (see ODBC specification).  e.g.

	 $value = $dbh->func(6, 'GetInfo');

       which returns the "SQL_DRIVER_NAME".

       This function returns a scalar value, which can be a numeric or string
       value depending on the information value requested.

       SQLGetTypeInfo

       This private function is now superceded by DBI's type_info and
       type_info_all methods.

       This function maps to the ODBC SQLGetTypeInfo API and the argument
       should be a SQL type number (e.g. SQL_VARCHAR) or SQL_ALL_TYPES.
       SQLGetTypeInfo returns information about a data type supported by the
       data source.

       e.g.

	 use DBI qw(:sql_types);

	 $sth = $dbh->func(SQL_ALL_TYPES, GetTypeInfo);
	 DBI::dump_results($sth);

       This function returns a DBI statement handle for the SQLGetTypeInfo
       result-set containing many columns of type attributes (see ODBC
       specification).

       NOTE: It is VERY important that the "use DBI" includes the
       "qw(:sql_types)" so that values like SQL_VARCHAR are correctly
       interpreted.  This "imports" the sql type names into the program's name
       space.  A very common mistake is to forget the "qw(:sql_types)" and
       obtain strange results.

       GetFunctions

       This function maps to the ODBC SQLGetFunctions API which returns
       information on whether a function is supported by the ODBC driver.

       The argument should be "SQL_API_ALL_FUNCTIONS" (0) for all functions or
       a valid ODBC function number (e.g. "SQL_API_SQLDESCRIBEPARAM" which is
       58). See ODBC specification or examine your sqlext.h and sql.h header
       files for all the SQL_API_XXX macros.

       If called with "SQL_API_ALL_FUNCTIONS" (0), then a 100 element array is
       returned where each element will contain a '1' if the ODBC function
       with that SQL_API_XXX index is supported or '' if it is not.

       If called with a specific SQL_API_XXX value for a single function it
       will return true if the ODBC driver supports that function, otherwise
       false.

       e.g.

	   my @x = $dbh->func(0,"GetFunctions");
	   print "SQLDescribeParam is supported\n" if ($x[58]);

       or

	   print "SQLDescribeParam is supported\n"
	       if $dbh->func(58, "GetFunctions");

       GetStatistics

       This private function is now superceded by DBI's statistics_info
       method.

       See the ODBC specification for the SQLStatistics API.  You call
       SQLStatistics like this:

	 $dbh->func($catalog, $schema, $table, $unique, 'GetStatistics');

       Prior to DBD::ODBC 1.16 $unique was not defined as being true/false or
       SQL_INDEX_UNIQUE/SQL_INDEX_ALL. In fact, whatever value you provided
       for $unique was passed through to the ODBC API SQLStatistics call
       unchanged. This changed in 1.16, where $unique became a true/false
       value which is interpreted into SQL_INDEX_UNIQUE for true and
       SQL_INDEX_ALL for false.

       GetForeignKeys

       This private function is now superceded by DBI's foreign_key_info
       method.

       See the ODBC specification for the SQLForeignKeys API.  You call
       SQLForeignKeys like this:

	 $dbh->func($pcatalog, $pschema, $ptable,
		    $fcatalog, $fschema, $ftable,
		    "GetForeignKeys");

       GetPrimaryKeys

       This private function is now superceded by DBI's primary_key_info
       method.

       See the ODBC specification for the SQLPrimaryKeys API.  You call
       SQLPrimaryKeys like this:

	 $dbh->func($catalog, $schema, $table, "GetPrimaryKeys");

       data_sources

       This private function is now superceded by DBI's data_sources method.

       You call data_sources like this:

	 @dsns = $dbh->func("data_sources);

       Handled since 0.21.

       GetSpecialColumns

       See the ODBC specification for the SQLSpecialColumns API.  You call
       SQLSpecialColumns like this:

	 $dbh->func($identifier, $catalog, $schema, $table, $scope,
		    $nullable, 'GetSpecialColumns');

       Handled as of version 0.28

       ColAttributes

       This private function is now superceded by DBI's statement attributes
       NAME, TYPE, PRECISION, SCALE, NULLABLE etc).

       See the ODBC specification for the SQLColAttributes API.	 You call
       SQLColAttributes like this:

	 $dbh->func($column, $ftype, "ColAttributes");

	 SQL_COLUMN_COUNT = 0
	 SQL_COLUMN_NAME = 1
	 SQL_COLUMN_TYPE = 2
	 SQL_COLUMN_LENGTH = 3
	 SQL_COLUMN_PRECISION = 4
	 SQL_COLUMN_SCALE = 5
	 SQL_COLUMN_DISPLAY_SIZE = 6
	 SQL_COLUMN_NULLABLE = 7
	 SQL_COLUMN_UNSIGNED = 8
	 SQL_COLUMN_MONEY = 9
	 SQL_COLUMN_UPDATABLE = 10
	 SQL_COLUMN_AUTO_INCREMENT = 11
	 SQL_COLUMN_CASE_SENSITIVE = 12
	 SQL_COLUMN_SEARCHABLE = 13
	 SQL_COLUMN_TYPE_NAME = 14
	 SQL_COLUMN_TABLE_NAME = 15
	 SQL_COLUMN_OWNER_NAME = 16
	 SQL_COLUMN_QUALIFIER_NAME = 17
	 SQL_COLUMN_LABEL = 18

       Note:Oracle's ODBC driver for linux in instant client 11r1 often
       returns strange values for column name e.g., '20291'. It is wiser to
       use DBI's NAME and NAME_xx attributes for portability.

       DescribeCol

       This private function is now superceded by DBI's statement attributes
       NAME, TYPE, PRECISION, SCLARE, NULLABLE etc).

       See the ODBC specification for the SQLDescribeCol API.  You call
       SQLDescribeCol like this:

	 @info = $dbh->func($column, "DescribeCol");

       The returned array contains the column attributes in the order
       described in the ODBC specification for SQLDescribeCol.

   Additional bind_col attributes
       DBD::ODBC supports a few additional attributes which may be passed to
       the bind_col method in the attributes.

       DiscardString

       See DBI's sql_type_cast utility function.

       If you bind a column as a specific type (SQL_INTEGER, SQL_DOUBLE and
       SQL_NUMERIC are the only ones supported currently) and you add
       DiscardString to the prepare attributes then if the returned bound data
       is capable of being converted to that type the scalar's pv (the string
       portion of a scalar) is cleared.

       This is especially useful if you are using a module which uses a
       scalars flags and/or pv to decide if a scalar is a number. JSON::XS
       does this and without this flag you have to add 0 to all bound column
       data returning numbers to get JSON::XS to encode it is N instead of
       "N".

       StrictlyTyped

       See DBI's sql_type_cast utility function.

       See "DiscardString" above.

       Specifies that when DBI's sql_type_cast function is called on returned
       data where a bind type is specified that if the conversion cannot be
       performed an error will be raised.

       This is probably not a lot of use with DBD::ODBC as if you ask for say
       an SQL_INTEGER and the data is not able to be converted to an integer
       the ODBC driver will problably return "Invalid character value for cast
       specification (SQL-22018)".

       TreatAsLOB

       See "odbc_lob_read".

   Tracing
       DBD::ODBC now supports the parse_trace_flag and parse_trace_flags
       methods introduced in DBI 1.42 (see DBI for a full description).	 As of
       DBI 1.604, the only trace flag defined which is relevant to DBD::ODBC
       is 'SQL' which DBD::ODBC supports by outputting the SQL strings (after
       modification) passed to the prepare and do methods.

       From DBI 1.617 DBI also defines ENC (encoding), CON (connection) TXN
       (transaction) and DBD (DBD only) trace flags. DBI's ENC and CON trace
       flags are synonomous with DBD::ODBC's odbcunicode and odbcconnection
       trace flags though I may remove the DBD::ODBC ones in the future. DBI's
       DBD trace flag allows output of only DBD::ODBC trace messages without
       DBI's trace messages.

       Currently DBD::ODBC supports two private trace flags. The 'odbcunicode'
       flag traces some unicode operations and the odbcconnection traces the
       connect process.

       To enable tracing of particular flags you use:

	 $h->trace($h->parse_trace_flags('SQL|odbcconnection'));
	 $h->trace($h->parse_trace_flags('1|odbcunicode'));

       In the first case 'SQL' and 'odbcconnection' tracing is enabled on $h.
       In the second case trace level 1 is set and 'odbcunicode' tracing is
       enabled.

       If you want to enable a DBD::ODBC private trace flag before connecting
       you need to do something like:

	 use DBD::ODBC;
	 DBI->trace(DBD::ODBC->parse_trace_flag('odbcconnection'));

       or

	 use DBD::ODBC;
	 DBI->trace(DBD::ODBC->parse_trace_flags('odbcconnection|odbcunicode'));

       or

	 DBI_TRACE=odbcconnection|odbcunicode perl myscript.pl

       From DBI 1.617 you can output only DBD::ODBC trace messages using

	 DBI_TRACE=DBD perl myscript.pl

       DBD::ODBC outputs tracing at levels 3 and above (as levels 1 and 2 are
       reserved for DBI).

       For comprehensive tracing of DBI method calls without all the DBI
       internals see DBIx::Log4perl.

   Deviations from the DBI specification
       last_insert_id

       DBD::ODBC does not support DBI's last_insert_id. There is no ODBC
       defined way of obtaining this information. Generally the mechanism (and
       it differs vastly between databases and ODBC drivers) it to issue a
       select of some form (e.g., select @@identity or select sequence.currval
       from dual, etc).

       There are literally dozens of databases and ODBC drivers supported by
       DBD::ODBC and I cannot have them all. If you know how to retrieve the
       information for last_insert_id and you mail me the ODBC Driver
       name/version and database name/version with a small working example I
       will collect examples and document them here.

       Microsoft Access. Recent versions of MS Access support select
       @@identity to retrieve the last insert ID.  See
       http://support.microsoft.com/kb/815629. Information provided by Robert
       Freimuth.

       Comments in SQL

       DBI does not say anything in particular about comments in SQL.
       DBD::ODBC looks for placeholders in the SQL string and until 1.24_2 it
       did not recognise comments in SQL strings so could find what it
       believes to be a placeholder in a comment e.g.,

	 select '1' /* placeholder ? in comment */
	 select -- named placeholder :named in comment
	   '1'

       I cannot be exact about support for ignoring placeholders in literals
       but it has existed for a long time in DBD::ODBC. Support for ignoring
       placeholders in comments was added in 1.24_2. If you find a case where
       a named placeholder is not ignored and should be, see
       "odbc_ignore_named_placeholders" for a workaround and mail me an
       example along with your ODBC driver name.

       do

       This is not really a deviation from the DBI specification since DBI
       allows a driver to avoid the overhead of creating an DBI statement
       handle for do().

       DBD::ODBC implements "do" by calling SQLExecDirect in ODBC and not
       SQLPrepare followed by SQLExecute so "do" is not the same as:

	 $dbh->prepare($sql)->execute()

       It does this to avoid a round-trip to the server so it is faster.
       Normally this is good but some people fall foul of this with MS SQL
       Server if they call a procedure which outputs print statements (e.g.,
       backup) as the procedure may not complete. See the DBD::ODBC FAQ and in
       general you are better to use prepare/execute when calling procedures.

       In addition, you should realise that since DBD::ODBC does not create a
       DBI statement for do calls, if you set up an error handler the handle
       passed in when a do fails will be the database handle and not a
       statement handle.

       Mixed placeholder types

       There are 3 conventions for place holders in DBI. These are '?', ':N'
       and ':name' (where 'N' is a number and 'name' is an alpha numeric
       string not beginning with a number). DBD::ODBC supports all these
       methods for naming placeholders but you must only use one method
       throughout a particular SQL string. If you mix placeholder methods you
       will get an error like:

	 Can't mix placeholder styles (1/2)

       Using the same placeholder more than once

       DBD::ODBC does not support (currently) the use of one named placeholder
       more than once in the a single SQL string. i.e.,

	 insert into foo values (:bar, :p1, :p2, :bar);

       is not supported because 'bar' is used more than once but:

	 insert into foo values(:bar, :p1, :p2)

       is ok. If you do the former you will get an error like:

	 DBD::ODBC does not yet support binding a named parameter more than once

       Binding named placeholders

       Although the DBI documentation (as of 1.604) does not say how named
       parameters are bound Tim Bunce has said that in Oracle they are bound
       with the leading ':' as part of the name and that has always been the
       case. i.e.,

	 prepare("insert into mytable values (:fred)");
	 bind_param(":foo", 1);

       DBD::ODBC does not support binding named parameters with the ':'
       introducer.  In the above example you must use:

	 bind_param("foo", 1);

       In discussion on the dbi-dev list is was suggested that the ':' could
       be made optional and there were no basic objections but it has not made
       it's way into the pod yet.

       Sticky Parameter Types

       The DBI specification post 1.608 says in bind_param:

	 The data type is 'sticky' in that bind values passed to execute()
	 are bound with the data type specified by earlier bind_param()
	 calls, if any.	 Portable applications should not rely on being able
	 to change the data type after the first C<bind_param> call.

       DBD::ODBC does allow a parameter to be rebound with another data type
       as ODBC inherently allows this. Therefore you can do:

	 # parameter 1 set as a SQL_LONGVARCHAR
	 $sth->bind_param(1, $data, DBI::SQL_LONGVARCHAR);
	 # without the bind above the $data parameter would be either a DBD::ODBC
	 # internal default or whatever the ODBC driver said it was but because
	 # parameter types are sticky, the type is still SQL_LONGVARCHAR.
	 $sth->execute($data);
	 # change the bound type to SQL_VARCHAR
	 # some DBDs will ignore the type in the following, DBD::ODBC does not
	 $sth->bind_param(1, $data, DBI::SQL_VARCHAR);

       disconnect and transactions

       DBI does not define whether a driver commits or rolls back any
       outstanding transaction when disconnect is called. As such DBD::ODBC
       cannot deviate from the specification but you should know it rolls back
       an uncommitted transaction when disconnect is called if SQLDisconnect
       returns state 25000 (transaction in progress).

   Unicode
       The ODBC specification supports wide character versions (a postfix of
       'W') of some of the normal ODBC APIs e.g., SQLDriverConnectW is a wide
       character version of SQLDriverConnect.

       In ODBC on Windows the wide characters are defined as SQLWCHARs (2
       bytes) and are UCS-2. On non-Windows, the main driver managers I know
       of have implemented the wide character APIs differently:

       unixODBC
	   unixODBC mimics the Windows ODBC API precisely meaning the wide
	   character versions expect and return 2-byte characters in UCS-2.

	   unixODBC will happily recognise ODBC drivers which only have the
	   ANSI versions of the ODBC API and those that have the wide versions
	   too.

	   unixODBC will allow an ANSI application to work with a unicode ODBC
	   driver and vice versa (although in the latter case you obviously
	   cannot actually use unicode).

	   unixODBC does not prevent you sending UTF-8 in the ANSI versions of
	   the ODBC APIs but whether that is understood by your ODBC driver is
	   another matter.

	   unixODBC differs in only one way from the Microsoft ODBC driver in
	   terms of unicode support in that it avoids unnecessary translations
	   between single byte and double byte characters when an ANSI
	   application is using a unicode-aware ODBC driver by requiring
	   unicode applications to signal their intent by calling
	   SQLDriverConnectW first. On Windows, the ODBC driver manager always
	   uses the wide versions of the ODBC API in ODBC drivers which
	   provide the wide versions regardless of what the application really
	   needs and this results in a lot of unnecessary character
	   translations when you have an ANSI application and a unicode ODBC
	   driver.

       iODBC
	   The wide character versions expect and return wchar_t types.

       DBD::ODBC has gone with unixODBC so you cannot use iODBC with a unicode
       build of DBD::ODBC. However, some ODBC drivers support UTF-8 (although
       how they do this with SQLGetData reliably I don't know) and so you
       should be able to use those with DBD::ODBC not built for unicode.

       Enabling and Disabling Unicode support

       On Windows Unicode support is enabled by default and to disable it you
       will need to specify "-nou" to Makefile.PL to get back to the original
       behavior of DBD::ODBC before any Unicode support was added.

       e.g.,

	 perl Makfile.PL -nou

       On non-Windows platforms Unicode support is disabled by default. To
       enable it specify "-u" to Makefile.PL when you configure DBD::ODBC.

       e.g.,

	 perl Makefile.PL -u

       Unicode - What is supported?

       As of version 1.17 DBD::ODBC has the following unicode support:

       SQL (introduced in 1.16_2)
	   Unicode strings in calls to the "prepare" and "do" methods are
	   supported so long as the "odbc_execdirect" attribute is not used.

       unicode connection strings (introduced in 1.16_2)
	   Unicode connection strings are supported but you will need a DBI
	   post 1.607 for that.

       column names
	   Unicode column names are returned.

       bound columns (introduced in 1.15)
	   If the DBMS reports the column as being a wide character (SQL_Wxxx)
	   it will be bound as a wide character and any returned data will be
	   converted from UTF16 to UTF8 and the UTF8 flag will then be set on
	   the data.

       bound parameters
	   If the perl scalars you bind to parameters are marked UTF8 and the
	   DBMS reports the type as being a wide type or you bind the
	   parameter as a wide type they will be converted to wide characters
	   and bound as such.

       Since version 1.16_4, the default parameter bind type is SQL_WVARCHAR
       for unicode builds of DBD::ODBC. This only affects ODBC drivers which
       do not support SQLDescribeParam and only then if you do not
       specifically set a sql type on the bind_param method call.

       The above Unicode support has been tested with the SQL Server, Oracle
       9.2+ and Postgres drivers on Windows and various Easysoft ODBC drivers
       on UNIX.

       Unicode - What is not supported?

       You cannot use unicode parameter names e.g.,

	 select * from table where column = :unicode_param_name

       You cannot use unicode strings in calls to prepare if you set the
       odbc_execdirect attribute.

       You cannot pass unicode catalog, schema, table and column names into
       metadata calls (like column_info) at present because the XS interface
       uses char * instead of Perl scalars. NOTE: as of DBD::ODBC 1.32_3
       Unicode is fully supported for input parameters in table_info. As of
       DBD::ODBC 1.32_5 Unicode is fully supported for input parameters in
       column_info.

       You cannot use the iODBC driver manager with DBD::ODBC built for
       unicode.

       Unicode - Caveats

       For Unicode support on any platform in Perl you will need at least Perl
       5.8.1 - sorry but this is the way it is with Perl.

       The Unicode support in DBD::ODBC expects a WCHAR to be 2 bytes (as it
       is on Windows and as the ODBC specification suggests it is). Until ODBC
       specifies any other Unicode support it is not envisioned this will
       change.	On UNIX there are a few different ODBC driver managers. I have
       only tested the unixODBC driver manager (http://www.unixodbc.org) with
       Unicode support and it was built with defaults which set WCHAR as 2
       bytes.

       I believe that the iODBC driver manager expects wide characters to be
       wchar_t types (which are usually 4) and hence DBD::ODBC will not work
       iODBC when built for unicode.

       The ODBC Driver must expect Unicode data specified in SQLBindParameter
       and SQLBindCol to be UTF16 in local endianness. Similarly, in calls to
       SQLPrepareW, SQLDescribeColW and SQLDriverConnectW.

       You should be aware that once Unicode support is enabled it affects a
       number of DBI methods (some of which you might not expect). For
       instance, when listing tables, columns etc some drivers (e.g. Microsoft
       SQL Server) will report the column types as wide types even if the
       strings actually fit in 7-bit ASCII. As a result, there is an overhead
       for retrieving this column data as 2 bytes per character will be
       transmitted (compared with 1 when Unicode support is not enabled) and
       these strings will be converted into UTF8 but will end up fitting (in
       most cases) into 7bit ASCII so a lot of conversion work has been
       performed for nothing. If you don't have Unicode table and column names
       or Unicode column data in your tables you are best disabling Unicode
       support.

       I am at present unsure if ChopBlanks processing on Unicode strings is
       working correctly on UNIX. If nothing else the construct L' ' in
       dbdimp.c might not work with all UNIX compilers. Reports of issues and
       patches welcome.

       Unicode implementation in DBD::ODBC

       DBD::ODBC uses the wide character versions of the ODBC API and the
       SQL_WCHAR ODBC type to support unicode in Perl.

       Wide characters returned from the ODBC driver will be converted to
       UTF-8 and the perl scalars will have the utf8 flag set (by using
       sv_utf8_decode).

       perl scalars which are UTF-8 and are sent through the ODBC API will be
       converted to UTF-16 and passed to the ODBC wide APIs or signalled as
       SQL_WCHARs (e.g., in the case of bound columns).

       When built for unicode, DBD::ODBC will always call SQLDriverConnectW
       (and not SQLDriverConnect) even if a) your connection string is not
       unicode b) you have not got a DBI later than 1.607, because unixODBC
       requires SQLDriverConnectW to be called if you want to call other
       unicode ODBC APIs later. As a result, if you build for unicode and pass
       ASCII strings to the connect method they will be converted to UTF-16
       and passed to SQLDriverConnectW. This should make no real difference to
       perl not using unicode connection strings.

       You will need a DBI later than 1.607 to support unicode connection
       strings because until post 1.607 there was no way for DBI to pass
       unicode strings to the DBD.

       Unicode and Oracle

       You have to set the environment variables "NLS_NCHAR=AL32UTF8" and
       "NLS_LANG=AMERICAN_AMERICA.AL32UTF8" (or any other language setting
       ending with ".AL32UTF8") before loading DBD::ODBC to make Oracle return
       Unicode data. (See also "Oracle and Unicode" in the POD of
       DBD::Oracle.)

       On Windows, using the Oracle ODBC Driver you have to enable the Force
       SQL_WCHAR support Workaround in the data source configuration to make
       Oracle return Unicode to a non-Unicode application. Alternatively, you
       can include "FWC=T" in your connect string.

       Unless you need to use ODBC, if you want Unicode support with Oracle
       you are better off using DBD::Oracle.

       Unicode and PostgreSQL

       See the odbc_utf8_on parameter to treat all strings as utf8.

       Some tests from the original DBD::ODBC 1.13 fail with PostgreSQL 8.0.3,
       so you may not want to use DBD::ODBC to connect to PostgreSQL 8.0.3.

       Unicode tests fail because PostgreSQL seems not to give any hints about
       Unicode, so all data is treated as non-Unicode.

       Unless you need to use ODBC, if you want Unicode support with Postgres
       you are better off with DBD::Pg as it has a specific attribute named
       "pg_enable_utf8" to enable Unicode support.

       Unicode and Easysoft ODBC Drivers

       We have tested the Easysoft SQL Server, Oracle and ODBC Bridge drivers
       with DBD::ODBC built for Unicode. All work as described without
       modification except for the Oracle driver you will need to set you
       NLS_LANG as mentioned above.

       Unicode and other ODBC drivers

       If you have a unicode-enabled ODBC driver and it works with DBD::ODBC
       let me know and I will include it here.

   ODBC Support in ODBC Drivers
       Drivers without SQLDescribeParam

       Some drivers do not support the "SQLDescribeParam" ODBC API (e.g.,
       Microsoft Access, FreeTDS).

       DBD::ODBC uses the "SQLDescribeParam" API when parameters are bound to
       your SQL to find the types of the parameters. If the ODBC driver does
       not support "SQLDescribeParam", DBD::ODBC assumes the parameters are
       "SQL_VARCHAR" or "SQL_WVARCHAR" types (depending on whether DBD::ODBC
       is built for unicode or not). In any case, if you bind a parameter and
       specify a SQL type this overrides any type DBD::ODBC would choose.

       For ODBC drivers which do not support "SQLDescribeParam" the default
       behavior in DBD::ODBC may not be what you want. To change the default
       parameter bind type set "odbc_default_bind_type". If, after that you
       have some SQL where you need to vary the parameter types used add the
       SQL type to the end of the "bind_param" method.

	 use DBI qw(:sql_types);
	 $h = DBI->connect;
	 # set the default bound parameter type
	 $h->{odbc_default_bind_type} = SQL_VARCHAR;
	 # bind a parameter with a specific type
	 $s = $h->prepare(q/insert into mytable values(?)/);
	 $s->bind_param(1, "\x{263a}", SQL_WVARCHAR);

   CPAN Testers Reporting
       Please, please, please (is that enough), consider installing
       CPAN::Reporter so that when you install perl modules a report of the
       installation success or failure can be sent to cpan testers. In this
       way module authors 1) get feedback on the fact that a module is being
       installed 2) get to know if there are any installation problems. Also
       other people like you may look at the test reports to see how
       successful they are before choosing the version of a module to install.

       See this guide on how to get started with sending test reports:
       <http://wiki.cpantesters.org/wiki/QuickStart>.

   Others/todo?
       Level 2

	   SQLColumnPrivileges
	   SQLProcedureColumns
	   SQLProcedures
	   SQLTablePrivileges
	   SQLDrivers
	   SQLNativeSql

   Random Links
       These are in need of sorting and annotating. Some are relevant only to
       ODBC developers.

       You can find DBD::ODBC on ohloh now at:

       <http://www.ohloh.net/projects/perl_dbd_odbc>

       If you use ohloh and DBD::ODBC please say you use it and rate it.

       There is a good search engine for the various Perl DBI lists at the
       following URLS:

       <http://perl.markmail.org/search/list:org.perl.dbi-users>

       <http://perl.markmail.org/search/list:org.perl.dbi-dev>

       <http://perl.markmail.org/search/list:org.perl.dbi-announce>

       <http://www.syware.com>

       <http://www.microsoft.com/odbc>

       For Linux/Unix folks, compatible ODBC driver managers can be found at:

       <http://www.unixodbc.org> (unixODBC source and rpms)

       <http://www.iodbc.org> (iODBC driver manager source)

       For Linux/Unix folks, you can checkout the following for ODBC Drivers
       and Bridges:

       <http://www.easysoft.com>

       <http://www.openlinksw.com>

       <http://www.datadirect.com>

       <http://www.atinet.com>

       Some useful tutorials:

       Debugging Perl DBI:

       <http://www.easysoft.com/developer/languages/perl/dbi-debugging.html>

       Enabling ODBC support in Perl with Perl DBI and DBD::ODBC:

       <http://www.easysoft.com/developer/languages/perl/dbi_dbd_odbc.html>

       Perl DBI/DBD::ODBC Tutorial Part 1 - Drivers, Data Sources and
       Connection:

       <http://www.easysoft.com/developer/languages/perl/dbd_odbc_tutorial_part_1.html>

       Perl DBI/DBD::ODBC Tutorial Part 2 - Introduction to retrieving data
       from your database:

       <http://www.easysoft.com/developer/languages/perl/dbd_odbc_tutorial_part_2.html>

       Perl DBI/DBD::ODBC Tutorial Part 3 - Connecting Perl on UNIX or Linux
       to Microsoft SQL Server:

       <http://www.easysoft.com/developer/languages/perl/sql_server_unix_tutorial.html>

       Perl DBI - Put Your Data On The Web:

       <http://www.easysoft.com/developer/languages/perl/tutorial_data_web.html>

       Multiple Active Statements (MAS) and DBD::ODBC

       <http://www.easysoft.com/developer/languages/perl/multiple-active-statements.html>

   Frequently Asked Questions
       Frequently asked questions are now in DBD::ODBC::FAQ. Run "perldoc
       DBD::ODBC::FAQ" to view them.

CONFIGURATION AND ENVIRONMENT
       You should consult the documentation for the ODBC Driver Manager you
       are using.

DEPENDENCIES
       DBI

       Test::Simple

INCOMPATIBILITIES
       None known.

BUGS AND LIMITATIONS
       None known other than the deviations from the DBI specification
       mentioned above in "Deviations from the DBI specification".

       Please report any to me via the CPAN RT system. See
       <http://rt.cpan.org/> for more details.

AUTHOR
       Tim Bunce

       Jeff Urlwin

       Thomas K. Wenrich

       Martin J. Evans

LICENSE AND COPYRIGHT
       This program is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself. See perlartistic. This program is
       distributed in the hope that it will be useful, but WITHOUT ANY
       WARRANTY; without even the implied warranty of MERCHANTABILITY or
       FITNESS FOR A PARTICULAR PURPOSE.

       Portions of this software are Copyright Tim Bunce, Thomas K. Wenrich,
       Jeff Urlwin and Martin J. Evans - see the source.

SEE ALSO
       DBI

perl v5.18.1			  2011-12-01			       ODBC(3)
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