Sybase IQ currently provides support for subqueries that is somewhat different from that provided by Adaptive Server Enterprise and SQL Anywhere. Adaptive Server Enterprise and SQL Anywhere support subqueries in the ON clause; Sybase IQ does not currently support this.
UNION in subqueries is supported as follows:
SQL Anywhere supports UNION in both correlated and uncorrelated subqueries.
Sybase IQ supports UNION only in uncorrelated subqueries.
Adaptive Server Enterprise does not support UNION in any subqueries.
SQL Anywhere supports subqueries in many additional places that a scalar value might appear in the grammar. Adaptive Server Enterprise and Sybase IQ follow the ANSI standard as to where subqueries can be specified.
