I have a table in a MySQL-DB which is of datatype "bit". The name of this column is "abk".

If I write the following statement:
SQLSelect[conn, {"dbtable_tooltips"}, {"begriff_en", "abk"}, 
 SQLMemberQ[deffindcrit, SQLColumn["geltungsbereich"]]]

Mathematica just responds the statement without doing that.

On the other hand if I send a statement with a wrong column-name (one that does not exist), it tells me that it doesn't exist.

So I think, that it realises that there is this column and the name is correct, but there is something else which is wrong.