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