MySQL AFTER UPDATE Triggers

AFTER UPDATE triggers execute after row modifications successfully persist.
Access both OLD (previous values) and NEW (updated values) for change detection.
Ideal for audit logging, recalculating aggregates, cache invalidation, and notifications.

Basic AFTER UPDATE Syntax

OLD/NEW in AFTER UPDATE
OLD = previous row values (before UPDATE).
NEW = current row values (after UPDATE).
Both read-only after UPDATE completes.

Change Detection Audit

Comprehensive Change Logging

Summary Table Recalculation

Cache Invalidation

Notification on Status Change

Cross-Table Updates

OLD/NEW Availability

Revenue Recalculation

Inventory Adjustment

Permissions Required

Testing AFTER UPDATE Trigger

Execution Sequence

1. UPDATE identifies affected rows
2. BEFORE UPDATE triggers execute
3. Row changes persist to table
4. AFTER UPDATE triggers execute (alphabetical order)

Performance Optimization

Common Use Cases

• Detailed audit trails with OLD/NEW comparison
• Aggregate/summary table maintenance
• Cache invalidation
• Cross-referencing table synchronization
• Business process notifications
• Compliance logging

Production Pattern: Complete Order Audit

Bulk UPDATE Performance

Error Handling

• Trigger failures roll back entire UPDATE
• Secondary table constraints respected
• Transactional consistency maintained

Important Notes

• Both OLD and NEW read-only after UPDATE
• Cannot modify triggering table
• Alphabetical execution order for multiple triggers
• WHERE clause optimizes conditional logging
• Perfect for "after the fact" processing

Advanced Conditional Logic

Key Points

• AFTER UPDATE fires post-successful modification
• OLD/NEW comparison enables change detection
• Perfect for audit trails and recalculations
• Can update other tables, not triggering table
• Transactional: failures roll back everything
• Use WHERE clauses for performance