Steffen Goeldner wrote: > > P.S.: It seems I'll have TO DO some 'empty string' research.
This is yet another case where ODBC and SQL/CLI differ :-( ODBC is quite clear about pattern value arguments: <http://msdn.microsoft.com/library/en-us/odbc/htm/odbcpattern_value_arguments.asp> | Passing a null pointer to a search pattern argument does not | constrain the search for that argument; that is, a null pointer | and the search pattern % (any characters) are equivalent. | However, a zero-length search pattern - that is, a valid pointer | to a string of length zero - matches only the empty string (""). ODBC says not much about empty strings in ordinary arguments in general. However, the doc's for special catalog functions say (e.g. for SQLColumns): | If a driver supports catalogs for some tables but not for others, | such as when the driver retrieves data from different DBMSs, an | empty string ("") denotes those tables that do not have catalogs. ODBC is quite silent about empty strings in identifier arguments. In my opinion, ODBC treats empty strings always as restriction criteria, i.e. they match the empty string. SQL/CLI gives very precise rules how arguments must be handled. Attached is a perlified version of these rules for SQLColumns(). As you can see, arguments of length zero are ignored when building the predicate. Thus, empty strings will not restrict the result set. Matching an empty string is only possible if METADATA_ID is TRUE and the argument is an empty quoted identifier ('""'). Steffen
SQLColumns.pl
Description: Perl program
