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A function is commonly used as an expression or query result and returns a value or table. A procedure is invoked to perform an operation and may accept output parameters. Triggers run implicitly. Transaction control differs by engine, so keep commit ownership explicit and test routines against the target database/version.

A trigger can modify other rows or tables implicitly during an insert or update. That makes the visible application statement an incomplete description of the transaction and can add locking or recursion. Document and test trigger effects, or move orchestration to an explicit routine/service when hidden behavior harms operability.