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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 deadlock detector aborts one transaction so another can progress. Capture lock and query evidence, then retry the whole business transaction only if its effects are safe to repeat. Use bounded attempts with jitter, consistent resource ordering, and idempotency for any external side effects.

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.