Practice sql Quizzes
Enhance your sql skills with carefully curated quizzes designed to improve concept clarity and real-world application. Each question reinforces key principles through active practice. Ideal for students and professionals, these quizzes help you learn faster, stay sharp and strengthen your overall technical expertise.
Explore All sql Quizzes
Learn sql step by step with interactive quizzes designed for beginners and learners revising key concepts. Build a strong foundation with clear, structured practice in sql.
Question 1
Which SQL statement is used to retrieve unique values from a column?
1
SELECT DISTINCT column_name FROM table_name;
2
SELECT DIFFERENT column_name FROM table_name;
3
SELECT column_name FROM table_name WHERE DISTINCT;
4
SELECT UNIQUE column_name FROM table_name;
Question 2
What does SQL stand for?
1
System Query Language
2
Sequential Query Language
3
Standardized Query Logic
4
Structured Query Language
Question 3
Which SQL command is used to remove all records from a table without deleting the table structure?
1
CLEAR
2
TRUNCATE
3
DELETE
4
DROP
Question 4
Which SQL join returns only the matching rows from both tables?
1
LEFT JOIN
2
RIGHT JOIN
3
INNER JOIN
4
FULL JOIN
Question 5
Which SQL constraint ensures that a column cannot have NULL values?
1
PRIMARY KEY
2
NOT NULL
3
CHECK
4
UNIQUE
Question 6
Which of the following is NOT an SQL aggregate function?
1
CONCAT()
2
COUNT()
3
SUM()
4
AVG()
Question 7
Which SQL clause is used to filter records from a table?
1
HAVING
2
GROUP BY
3
ORDER BY
4
WHERE
Question 8
Which SQL JOIN returns all records from the left table and only matching records from the right table?
1
LEFT JOIN
2
INNER JOIN
3
FULL JOIN
4
RIGHT JOIN
Question 9
Which constraint is used to ensure that all values in a column are unique?
1
NOT NULL
2
UNIQUE
3
CHECK
4
FOREIGN KEY
Question 10
Which SQL clause is used with aggregate functions to group results?
1
HAVING
2
GROUP BY
3
ORDER BY
4
DISTINCT
Question 11
Which database index type speeds up text searches in SQL?
1
Full-Text Index
2
B-Tree Index
3
Clustered Index
4
Hash Index
Question 12
Which SQL command is used to permanently save changes in a transaction?
1
DELETE
2
ROLLBACK
3
SAVEPOINT
4
COMMIT
Question 13
Which normal form removes partial dependency?
1
3NF
2
1NF
3
BCNF
4
2NF
Question 14
Which SQL command creates a virtual table?
1
CREATE TABLE
2
CREATE VIEW
3
CREATE PROCEDURE
4
CREATE INDEX
Question 15
Which keyword is used to define an output parameter in an SQL stored procedure?
1
OUT
2
RETURN
3
RESULT
4
OUTPUT
Question 16
Which of the following SQL commands is used to remove all records from a table but keep its structure?
1
TRUNCATE
2
ALTER
3
DROP
4
DELETE
Question 17
Which SQL clause is evaluated after the GROUP BY clause?
1
HAVING
2
ORDER BY
3
WHERE
4
DISTINCT
Question 18
What will happen if you use DELETE without a WHERE clause?
1
All rows will be deleted
2
Table structure will be deleted
3
SQL error will occur
4
Only one row will be deleted
Question 19
Which SQL keyword is used to sort the result set?
1
FILTER
2
GROUP BY
3
ORDER BY
4
SORT
Question 20
Which SQL function returns the total number of rows, including NULL values?
1
COUNT(column_name)
2
COUNT(*)
3
SUM()
4
TOTAL()
Question 21
Which SQL statement is used to add a new column to an existing table?
1
ALTER TABLE
2
UPDATE TABLE
3
ADD COLUMN
4
MODIFY TABLE
Question 22
Which SQL operator is used to search for a specified pattern?
1
LIKE
2
EXISTS
3
BETWEEN
4
IN
Question 23
What is the purpose of the EXISTS keyword in SQL?
1
Checks if a subquery returns any rows
2
Checks for NULL values
3
Checks if a table exists
4
Verifies column existence
Question 24
Which isolation level allows dirty reads?
1
READ COMMITTED
2
READ UNCOMMITTED
3
SERIALIZABLE
4
REPEATABLE READ
Question 25
Which SQL statement is used to rename a table?
1
MODIFY TABLE
2
CHANGE TABLE
3
RENAME TABLE
4
ALTER NAME
Question 26
Which index improves performance when queries frequently use range conditions?
1
B-Tree Index
2
Bitmap Index
3
Full-Text Index
4
Hash Index
Question 27
What is the main advantage of using window functions in SQL?
1
They replace subqueries completely
2
They allow aggregation without grouping rows
3
They improve indexing performance
4
They modify the original table data
Question 28
Which scenario is most suitable for using a CTE (Common Table Expression)?
1
When simplifying complex recursive or multi-step queries
2
When improving table indexing
3
When replacing transactions
4
When permanent storage is required
Question 29
Which SQL join can be used to find records that exist in one table but not in another?
1
LEFT JOIN with NULL check
2
INNER JOIN
3
FULL JOIN
4
CROSS JOIN
Question 30
Which index type is most effective for columns with low cardinality?
1
B-Tree Index
2
Bitmap Index
3
Hash Index
4
Full-Text Index