What Is Database Testing?

Database testing is the process of verifying backend data stored in a database to ensure it is accurate, consistent, complete, and aligned with business rules. While UI testing checks what users see, database testing validates what actually gets stored behind the scenes.

In interviews, basic database testing interview questions focus on:

Understanding database concepts
Writing simple to intermediate SQL queries
Validating CRUD operations
Explaining real-time data scenarios

Why Database Testing Is Used

To ensure UI data = database data
To prevent duplicate, missing, or incorrect records
To validate business logic at DB level
To confirm data integrity and relationships

Database testing is especially important in banking, healthcare, insurance, and e-commerce applications.

Step 1: Understand Business Requirements

What data should be stored?
Which fields are mandatory?
What default values should be applied?

Step 2: Validate Schemas & Tables

Table names
Column names
Data types
Field length

Step 3: Validate Constraints

Primary Key
Foreign Key
NOT NULL
UNIQUE
CHECK

Step 4: CRUD Operations Validation

Operation	Description	SQL Used
Create	Insert new data	INSERT
Read	Fetch data	SELECT
Update	Modify data	UPDATE
Delete	Remove data	DELETE

Step 5: Validate Advanced Objects (Basic Level)

Indexes (basic understanding)
Stored Procedures
Triggers
Audit / log tables

Basic Database Testing Interview Questions (100+ Q&A)

Basic Database Concepts (1–20)

1. What is database testing?

Database testing validates backend data using SQL queries to ensure correctness and integrity.

2. Why is database testing important?

Because incorrect data can lead to wrong reports, financial loss, or system failure.

3. What skills are required for database testing?

Basic SQL knowledge
Understanding of tables and relationships
Business logic awareness

4. What is CRUD?

Create – INSERT
Read – SELECT
Update – UPDATE
Delete – DELETE

5. What is a primary key?

A column that uniquely identifies each record.

6. What is a foreign key?

A column that creates a relationship between two tables.

7. What is data integrity?

Ensuring data is accurate and consistent.

8. What is a table?

A structured collection of rows and columns.

9. What is a column?

A field that stores a specific type of data.

10. What is a row?

A single record in a table.

11. What is a schema?

A logical container for database objects.

12. What is normalization?

Reducing data redundancy.

13. What is denormalization?

Adding redundancy to improve performance.

14. What is a constraint?

Rules applied to table columns.

15. Types of constraints?

NOT NULL
UNIQUE
PRIMARY KEY
FOREIGN KEY

16. What is NULL?

Represents missing or unknown data.

17. What is a default value?

Automatically assigned value if none is provided.

18. What is a view?

A virtual table based on a query.

19. What is an index?

Improves query performance.

20. Difference between database and schema?

Database stores data; schema organizes objects.

Basic SQL Interview Questions for Testing (21–45)

21. Fetch all records from a table

SELECT * FROM users;

22. Fetch specific columns

SELECT name, email FROM users;

23. Fetch records with a condition

SELECT * FROM users WHERE age > 25;

24. Fetch unique values

SELECT DISTINCT city FROM customers;

25. Sort records

SELECT * FROM orders ORDER BY created_date DESC;

26. Count number of records

SELECT COUNT(*) FROM users;

27. What is GROUP BY?

Groups rows with similar values.

SELECT department, COUNT(*)

FROM employees

GROUP BY department;

28. What is HAVING?

Filters grouped data.

SELECT department, COUNT(*)

FROM employees

GROUP BY department

HAVING COUNT(*) > 5;

29. Difference between WHERE and HAVING?

WHERE	HAVING
Filters rows	Filters groups
Used before GROUP BY	Used after GROUP BY

30. What is BETWEEN?

SELECT * FROM employees WHERE salary BETWEEN 30000 AND 60000;

JOIN-Based Basic Database Testing Questions (46–65)

46. What is a JOIN?

Combines data from multiple tables.

47. Types of JOINs

INNER JOIN
LEFT JOIN
RIGHT JOIN
FULL JOIN

48. INNER JOIN example

SELECT o.order_id, c.name

FROM orders o

INNER JOIN customers c

ON o.customer_id = c.id;

49. LEFT JOIN example

SELECT c.name, o.order_id

FROM customers c

LEFT JOIN orders o

ON c.id = o.customer_id;

50. Scenario: Customers with no orders

SELECT c.id

FROM customers c

LEFT JOIN orders o

ON c.id = o.customer_id

WHERE o.id IS NULL;

51. What is a self JOIN?

Joining a table with itself.

52. Why JOINs are important in database testing?

To validate relationships between tables.

Indexes, Stored Procedures & Triggers (66–85)

66. What is an index?

Improves query speed.

67. Why indexes are important?

They reduce full table scans.

68. What is a stored procedure?

Pre-compiled SQL logic stored in database.

69. Stored procedure example

CREATE PROCEDURE getUser(IN uid INT)

BEGIN

SELECT * FROM users WHERE id = uid;

END;

70. How do testers validate stored procedures?

Input values
Output results
Error handling

71. What is a trigger?

Automatically executes SQL on data change.

72. Trigger example

CREATE TRIGGER log_insert

AFTER INSERT ON orders

FOR EACH ROW

INSERT INTO audit_log VALUES (NEW.id, NOW());

73. Why triggers are tested?

To ensure logs and audit records are created.

Scenario Based Database Testing Interview Questions (86–110)

86. Scenario: Validate user registration

Record inserted
Default status applied

SELECT * FROM users WHERE email=’test@gmail.com’;

87. Scenario: Validate update operation

SELECT address FROM users WHERE id=101;

88. Scenario: Validate delete operation

SELECT * FROM users WHERE id=101;

89. Scenario: Validate soft delete

SELECT * FROM users WHERE is_active=’N’;

90. Scenario: Duplicate records check

SELECT email, COUNT(*)

FROM users

GROUP BY email

HAVING COUNT(*) > 1;

91. Scenario: Validate order & payment mapping

SELECT o.id, p.amount