Quiz for MERGE

Q1: What is the purpose of the MERGE statement in SQL?

A. To combine INSERT, UPDATE, and DELETE in one statement B. To combine tables C. To drop a table D. To add constraints

Q2: Which clause is mandatory in a MERGE statement?

A. USING B. WHERE C. HAVING D. GROUP BY

Q3: Which SQL keyword is used to define the matching condition in MERGE?

A. ON B. INTO C. WHERE D. HAVING

Q4: Which clause is used to define what happens when a match is found in MERGE?

A. WHEN MATCHED B. IF EXISTS C. THEN MATCHED D. DO MATCHED

Q5: Which clause is used to define actions when no match is found in MERGE?

A. WHEN NOT MATCHED B. IF NOT EXISTS C. ELSE D. ON NOT FOUND

Q6: Can the MERGE statement perform a DELETE?

A. Yes, with WHEN MATCHED THEN DELETE B. No, only INSERT and UPDATE C. Only in Oracle D. Only in SQL Server

Q7: Is MERGE part of the SQL standard?

A. Yes, from SQL:2003 onwards B. No, it is only vendor-specific C. Only in SQL:2016 D. No, never

Q8: Which database supports the MERGE statement?

A. Oracle B. MySQL C. SQLite D. All of the above

Q9: What happens if multiple source rows match one target row in MERGE?

A. It causes an error B. It performs multiple updates C. It inserts new rows D. It skips the row

Q10: Can you use MERGE with a temporary table?

A. Yes B. No C. Only in Oracle D. Only with privileges

Q11: What is the first keyword in a MERGE statement?

A. MERGE B. SELECT C. UPDATE D. INSERT

Q12: Which keyword follows MERGE in syntax?

A. INTO B. FROM C. TO D. WITH

Q13: How many target tables can be updated in one MERGE?

A. Only one B. Multiple C. Unlimited D. Depends on DBMS

Q14: Which clause is used to specify INSERT actions in MERGE?

A. WHEN NOT MATCHED THEN INSERT B. WHEN INSERT C. INSERT ON MISSING D. ON INSERT

Q15: MERGE helps reduce the need for which of the following?

A. Multiple separate DML statements B. Stored procedures C. Views D. Constraints

Q16: Which is true about MERGE performance?

A. It is faster than separate INSERT/UPDATE B. It is always slower C. It creates indexes D. It cannot be optimized

Q17: What is needed in the USING clause?

A. Source table or subquery B. Target table only C. Join clause D. WHERE clause

Q18: Can MERGE be rolled back if an error occurs?

A. Yes, if wrapped in a transaction B. No C. Only if INSERT fails D. Only in SQL Server

Q19: Does MySQL support the MERGE statement?

A. No, but REPLACE or INSERT ON DUPLICATE KEY can be used B. Yes C. Partially D. Only with plugins

Q20: What is another name for MERGE in some databases?

A. Upsert B. Downsert C. Subsert D. Expand