[Dbix-class] MSSQL notes

[Alan Humphrey]

Additional notes for anyone using MSSQL:

 

1) using the ODBC driver on Windows I had to use the software_limit
attribute:

 

$it = MSSQLTest::Artist->search( { },

            { rows => 3,

                software_limit => 1

            }

            );

 

Failure to use the attribute results in

 

SQL::Abstract::Limit: Unsupported data struct HASH for ORDER BY at
/usr/lib/perl5/site_perl/5.8/DBIx/Class/Storage/DBI.pm line 332

 

This is caused by this piece of code in _select (in DBI.pm)

 

  if (exists $attrs->{group_by}) {

    $order = { group_by => $attrs->{group_by},

               ($order ? (order_by => $order) : ()) };

  }

 

In my testing $attrs->{group_by} exists, but is undefined.

 

2) Using the DBD::Sybase driver on a BSD box I also have to set
limit_dialect:

 

$obj = $prod->resultset('Urls')->search({},

                                    {rows=>4,

                                    software_limit=>1

                                    });

 

$obj->result_source->storage->sql_maker->limit_dialect('Top');

 

Failure to set limit_dialect results in this error:

 

        (in cleanup) Can't call method "FETCH" on an undefined value at
/usr/pkg/lib/perl5/site_perl/5.8.0/DBIx/Class/Storage/DBI/Cursor.pm line 66
during global destruction.

 

 

3) If the offset attribute is used then I do not have to set limit_dialect:

 

$obj = $prod->resultset('Urls')->search({},

                                    {rows=>4,

                                     offset=>2,

                                    software_limit=>1

                                    });

 

I'm reasonably confident that the behavior seen in 2) and 3) is a result of
different code paths taken in SQL::Abstract::Limit based on the driver.

 

Use this info with caution. It's what worked for me, in my limited tests.
Also, both software_limit and limit_dialect are "public" methods (no leading
underscore), but they're undocumented.  I don't know what Matt has in mind
for them.

 

 

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