Log Message:
-----------
Check that a defining query has a value before using it.
Modified Files:
--------------
Npgsql2/src/Npgsql/SqlGenerators:
SqlBaseGenerator.cs (r1.8 -> r1.9)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/npgsql/Npgsql2/src/Npgsql/SqlGenerators/SqlBaseGenerator.cs.diff?r1=1.8&r2=1.9)