Query requirements differ between Adaptive Server Enterprise, SQL Anywhere,
and Sybase IQ.
General Guidelines for Writing Portable SQL
Even if more than one server supports a given SQL statement, it might be a mistake to assume that default behavior is the same on each system.
Subquery Support
Sybase IQ currently provides support for subqueries that is somewhat different from that provided by Adaptive Server Enterprise and SQL Anywhere.
GROUP BY Clause Support
GROUP BY ALL support differs between Adaptive Server Enterprise, SQL Anywhere, and Sybase IQ.
COMPUTE Clause Support
COMPUTE support differs between Adaptive Server Enterprise, SQL Anywhere, and Sybase IQ.
WHERE Clause Support
The WHERE clause differs between Adaptive Server Enterprise, SQL Anywhere, and Sybase IQ in support for the Contains() predicate, and treatment of trailing white space in the Like() predicate.
Transact-SQL Outer Joins Support
Supported syntax for outer joins differs between Adaptive Server Enterprise, SQL Anywhere, and Sybase IQ.
ANSI Joins Support
Support for ANSI join syntax differs between Adaptive Server Enterprise, SQL Anywhere, and Sybase IQ.
Null Comparisons Support
Adaptive Server Enterprise has Transact-SQL extensions that permit predicates to compare the null value.
Zero-length Strings Support
Zero-length strings are treated differently in Adaptive Server Enterprise, SQL Anywhere, and Sybase IQ.
SELECT INTO Statement Support
There are differences in the types of tables permitted in SELECT INTO statements in Adaptive Server Enterprise, SQL Anywhere, and Sybase IQ.
Updatable Views Support
Adaptive Server Enterprise and SQL Anywhere are more liberal than ANSI permits on the view definitions that are updatable when the WITH CHECK option is not requested.
Support for FROM Clause in UPDATE and DELETE
Sybase IQAdaptive Server Enterprise, SQL Anywhere, and Sybase IQ all support the FROM clause with multiple tables in UPDATE and DELETE.