A stored procedure auto-executing on INSERT/UPDATE/DELETE?
Interviewer Expectations for this Question
01
Core Competency
Assesses fundamental understanding of SQL & Databases conventions, runtime behavior, and memory/performance considerations.
02
Evaluation Criteria
Hiring managers look for precision, avoidance of ambiguous jargon, and ability to explain trade-offs under real production conditions.
Comprehensive Model Answer
Verified Solution
A specialized database procedure that automatically executes in response to data modification events (INSERT, UPDATE, or DELETE) on a specific table is called a Trigger:
CREATE TRIGGER before_order_insert
BEFORE INSERT ON orders
FOR EACH ROW
BEGIN
IF NEW.order_total < 0 THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE_TEXT = 'Order total cannot be negative';
END IF;
END;
### Common Use Cases for Triggers:
- Automated audit logging (recording who modified a record and when into an audit table).
- Enforcing complex multi-table business validation rules.
- Maintaining real-time summary aggregation tables.
Candidate Response Strategy & Interview Tips
- Start with a concise one-sentence summary: Deliver a direct, confident answer first before expanding into nuances.
- Demonstrate real-world trade-offs: Discuss where this approach excels and when you would avoid it in production systems.
- Discuss complexity & edge cases: Proactively explain time/space complexity or boundary conditions (null values, scale limits).
- Prepare for interviewer follow-ups: Technical hiring panels frequently probe deeper into concurrency, backward compatibility, or alternative libraries.