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DBI::DBD::Metadata(3)                User Contributed Perl Documentation               DBI::DBD::Metadata(3)



NAME
       DBI::DBD::Metadata - Generate the code and data for some DBI metadata methods

SYNOPSIS
       The idea is to extract metadata information from a good quality ODBC driver and use it to generate
       code and data to use in your own DBI driver for the same database.

       For generating code to support the get_info method:

         perl -MDBI::DBD::Metadata -e "write_getinfo_pm('dbi:ODBC:dsn-name','user','pass','Driver')"

         perl -MDBI::DBD::Metadata -e write_getinfo_pm dbi:ODBC:foo_db username password Driver

       For generating code to support the type_info method:

         perl -MDBI::DBD::Metadata -e "write_typeinfo_pm('dbi:ODBC:dsn-name','user','pass','Driver')"

         perl -MDBI::DBD::Metadata -e write_typeinfo_pm dbi:ODBC:dsn-name user pass Driver

       Where "dbi:ODBC:dsn-name" is the connection to use to extract the data, and "Driver" is the name of
       the driver you want the code generated for (the driver name gets embedded into the output in many
       places).

Generating a GetInfo package for a driver
       The "write_getinfo_pm" in the DBI::DBD::Metadata module generates a DBD::Driver::GetInfo package on
       standard output.

       This method generates a DBD::Driver::GetInfo package from the data source you specified in the
       parameter list or in the environment variable DBI_DSN.  DBD::Driver::GetInfo should help a DBD author
       implementing the DBI get_info() method.  Because you are just creating this package, it's very
       unlikely that DBD::Driver already provides a good implementation for get_info().  Thus you will
       probably connect via DBD::ODBC.

       Once you are sure that it is producing semi-sane data, you would typically redirect the standard
       output to lib/DBD/Driver/GetInfo.pm, and then hand edit the result.  Do not forget to update your
       Makefile.PL and MANIFEST to include this as an extra PM file that should be installed.

       If you connect via DBD::ODBC, you should use version 0.38 or greater;

       Please take a critical look at the data returned!  ODBC drivers vary dramatically in their quality.

       The generator assumes that most values are static and places these values directly in the %info hash.
       A few examples show the use of CODE references and the implementation via subroutines.  It is very
       likely that you have to write additional subroutines for values depending on the session state or
       server version, e.g.  SQL_DBMS_VER.

       A possible implementation of DBD::Driver::db::get_info() may look like:

         sub get_info {
           my($dbh, $info_type) = @_;
           require DBD::Driver::GetInfo;
           my $v = $DBD::Driver::GetInfo::info{int($info_type)};
           $v = $v->($dbh) if ref $v eq 'CODE';
           return $v;
         }

       Please replace Driver (or "<foo>") with the name of your driver.  Note that this stub function is
       generated for you by write_getinfo_pm function, but you must manually transfer the code to Driver.pm.

Generating a TypeInfo package for a driver
       The "write_typeinfo_pm" function in the DBI::DBD::Metadata module generates on standard output the
       data needed for a driver's type_info_all method.  It also provides default implementations of the
       type_info_all method for inclusion in the driver's main implementation file.

       The driver parameter is the name of the driver for which the methods will be generated; for the sake
       of examples, this will be "Driver".  Typically, the dsn parameter will be of the form
       "dbi:ODBC:odbc_dsn", where the odbc_dsn is a DSN for one of the driver's databases.  The user and
       pass parameters are the other optional connection parameters that will be provided to the DBI connect
       method.

       Once you are sure that it is producing semi-sane data, you would typically redirect the standard
       output to lib/DBD/Driver/TypeInfo.pm, and then hand edit the result if necessary.  Do not forget to
       update your Makefile.PL and MANIFEST to include this as an extra PM file that should be installed.

       Please take a critical look at the data returned!  ODBC drivers vary dramatically in their quality.

       The generator assumes that all the values are static and places these values directly in the %info
       hash.

       A possible implementation of DBD::Driver::type_info_all() may look like:

         sub type_info_all {
           my ($dbh) = @_;
           require DBD::Driver::TypeInfo;
           return [ @$DBD::Driver::TypeInfo::type_info_all ];
         }

       Please replace Driver (or "<foo>") with the name of your driver.  Note that this stub function is
       generated for you by the write_typeinfo_pm function, but you must manually transfer the code to
       Driver.pm.

AUTHORS
       Jonathan Leffler <jleffler@us.ibm.com> (previously <jleffler@informix.com>), Jochen Wiedmann
       <joe@ispsoft.de>, Steffen Goeldner <sgoeldner@cpan.org>, and Tim Bunce <dbi-users@perl.org>.



perl v5.8.8                                      2006-02-07                            DBI::DBD::Metadata(3)