Which statements are DDL?
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
DDL stands for Data Definition Language. DDL statements define, alter, and destroy database schema structures (tables, indexes, views, schemas, constraints):
### Primary DDL Statements:
CREATE: Creates new database objects (CREATE TABLE,CREATE INDEX).ALTER: Modifies the structure of existing objects (ALTER TABLE ADD COLUMN).DROP: Permanently deletes objects from the database catalog (DROP TABLE).TRUNCATE: Rapidly deletes all records from a table while preserving table schema.RENAME: Renames a table or database object.
*Key Characteristic:* In many databases (like MySQL and Oracle), DDL statements trigger an implicit COMMIT, meaning they cannot be rolled back.
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.