Ok then. I don't know of an existing module that does that, so I'm guessing you'll have to roll your own. Shouldn't be that tough - you can use the database handle function get_info. Here are the get_info numbers that can be used as parameters:

Type  Name                        Example A     Example B
 ----  --------------------------  ------------  ----------------
   17  SQL_DBMS_NAME               'ACCESS'      'Oracle'
   18  SQL_DBMS_VER                '03.50.0000'  '08.01.0721 ...'
   29  SQL_IDENTIFIER_QUOTE_CHAR   '`'           '"'
   41  SQL_CATALOG_NAME_SEPARATOR  '.'           '@'
  114  SQL_CATALOG_LOCATION        1             2
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so you could use

   my $dbms_name = $dbh->get_info(17);
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your new function could take in the $dbh handle, and call get_info(17) to get the dbms name, and once you know the name, you can construct the database specific SQL that will get you the day of the week for that database.

HTH.