the most stupid standard i have ever seen

The standard says that a BOOLEAN may be one of the following literals:

• TRUE
• FALSE
• UNKNOWN or NULL (unless prohibited by a NOT NULL constraint)

the boolean values in any sane boleean system are True or false , noooh sql should have other values so you should check them for the not NULL values , more work for nothing

http://troels.arvin.dk/db/rdbms/#data_types-boolean


.:(firebird):..:(databases):..:(sql):.