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ActivePerl 5.14 Documentation

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DBD::ODBC - ODBC Driver for DBI


NAME

DBD::ODBC - ODBC Driver for DBI


VERSION

This documentation refers to DBD::ODBC version 1.31.


SYNOPSIS

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

See the DBI manpage 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 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 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 (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 (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});

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 the DBIx::Log4perl manpage.

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 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 the DBD::Oracle manpage.

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 the DBD::Pg manpage 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 the DBD::ODBC::FAQ manpage. 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

the DBI manpage

the Test::Simple manpage


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 the perlartistic manpage. 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

the DBI manpage