I use some not so complex stored procedure. They ALWAYS return one row with one cell ( eventually empty ). I aslo tried to make the procedure return a tuple with two cells including one 'fake' never empty.

The stored procedure is not recognized as a 'select' and hence query.next() is equivalent to false. It seems that the presence of insert/updates within the procedure makes the isSelect return false.

a detailed description can be found here ( where code is readable )

http://stackoverflow.com/questions/19453286/isselect-qsqlquery-not-working-as-expected