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.
SQL Anywhere offers the ANSI_UPDATE_CONSTRAINTS option to control whether updates are restricted to those supported by SQL92, or a more liberal set of rules.
SAP Sybase IQ permits UPDATE only on single-table views that can be flattened. SAP Sybase IQ does not support WITH CHECK.