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DBI::DBD::Metadata(3) User Contributed Perl DocumentationDBI::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 MANI-
       FEST 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 exam-
       ples, 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 con-
       nection 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 Make-
       file.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 <jlefflerATus.com> (previously <jlefflerATinformix.com>), Jochen Wiedmann <joeATispsoft.de>,
       Steffen Goeldner <sgoeldnerATcpan.org>, and Tim Bunce <dbi-usersATperl.org>.



perl v5.8.8                       2007-10-10             DBI::DBD::Metadata(3)