Triggers firing other triggers   Suppose a trigger performs an action that would, if performed directly by a user, fire another trigger. SQL Anywhere and Adaptive Server Enterprise respond slightly differently to this situation. By default in Adaptive Server Enterprise, triggers fire other triggers up to a configurable nesting level, which has the default value of 16. You can control the nesting level with the Adaptive Server Enterprise nested triggers option. In SQL Anywhere, triggers fire other triggers without limit unless there is insufficient memory.

Triggers firing themselves   Suppose a trigger performs an action that would, if performed directly by a user, fire the same trigger. SQL Anywhere and Adaptive Server Enterprise respond slightly differently to this situation. By default, in SQL Anywhere, non-Transact-SQL triggers fire themselves recursively, whereas Transact-SQL dialect triggers do not fire themselves recursively. However, for Transact-SQL dialect triggers, you can use the self_recursion option of the SET statement [T-SQL] to allow a trigger to call itself recursively. See SET statement [T-SQL].

By default in Adaptive Server Enterprise, a trigger does not call itself recursively, but you can use the self_recursion option to allow recursion to occur.

ROLLBACK statement in triggers in triggers not supported   Adaptive Server Enterprise permits the ROLLBACK TRANSACTION statement within triggers, to roll back the entire transaction of which the trigger is a part. SQL Anywhere does not permit ROLLBACK (or ROLLBACK TRANSACTION) statements in triggers because a triggering action and its trigger together form an atomic statement.

SQL Anywhere does provide the Adaptive Server Enterprise-compatible ROLLBACK TRIGGER statement to undo actions within triggers. See ROLLBACK TRIGGER statement.

ORDER clause not supported   Transact-SQL triggers do not permit an ORDER nn clause; the value of trigger_order is automatically set to 1. This can cause an error to be returned creating a T-SQL trigger if there is already a statement level trigger. This is because the SYSTRIGGER system table has a unique index on table_id, event, trigger_time, trigger_order. For a particular event (insert, update, delete) statement-level triggers are always AFTER and trigger_order cannot be set, so there can be only one per table, assuming any other triggers do not set an order other than 1.