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