Quiz for DELETE

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

A. To remove data from a table B. To remove a table C. To remove a column D. To remove a database

Q2: Which keyword is used with DELETE to specify which rows should be removed?

A. SELECT B. FROM C. WHERE D. ORDER BY

Q3: What happens if you run DELETE FROM table_name without a WHERE clause?

A. Only first row deleted B. All rows deleted C. Syntax error D. Only last row deleted

Q4: Can DELETE statement be rolled back?

A. Yes B. No C. Only with AUTO_COMMIT D. Only in MySQL

Q5: Which command deletes all records from a table named Customers?

A. REMOVE FROM Customers; B. DELETE * FROM Customers; C. DELETE FROM Customers; D. CLEAR Customers;

Q6: Which of the following can improve DELETE performance?

A. Indexing WHERE columns B. Removing primary key C. Disabling constraints D. Using subqueries

Q7: What will DELETE FROM Orders WHERE OrderID = 105 do?

A. Deletes entire table B. Deletes all orders C. Deletes order with ID 105 D. Deletes all except ID 105

Q8: Which clause cannot be used with DELETE?

A. WHERE B. ORDER BY C. LIMIT D. GROUP BY

Q9: Which is safer for deleting data with condition?

A. DELETE without WHERE B. DELETE with WHERE C. TRUNCATE D. DROP

Q10: Which SQL statement is valid?

A. DELETE Customers; B. DELETE * Customers; C. DELETE FROM Customers; D. REMOVE FROM Customers;

Q11: How to delete rows where age is NULL in users table?

A. DELETE FROM users WHERE age = NULL; B. DELETE FROM users WHERE age IS NULL; C. DELETE users WHERE age == NULL; D. DELETE users WHERE age NULL;

Q12: How to delete duplicate rows using DELETE?

A. Use ORDER BY B. Use GROUP BY C. Use subquery with ROW_NUMBER() D. Use SELECT DISTINCT

Q13: Which privilege is required to execute DELETE?

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

Q14: What does DELETE do to the table structure?

A. Deletes structure too B. Keeps structure intact C. Drops columns D. Renames table

Q15: What type of operation is DELETE?

A. DDL B. DCL C. DML D. TCL

Q16: Which database constraint can prevent DELETE operation?

A. PRIMARY KEY B. CHECK C. FOREIGN KEY D. NOT NULL

Q17: Which is faster: DELETE or TRUNCATE?

A. DELETE B. TRUNCATE C. Both same D. Depends on DB

Q18: Which clause helps delete top 5 rows?

A. TOP 5 B. LIMIT 5 C. ROWNUM <= 5 D. All of the above (DB-specific)

Q19: DELETE FROM employees WHERE salary < 30000; will do what?

A. Delete all B. Delete employees earning below 30000 C. Raise error D. Delete employees earning above 30000