What Is Database Testing?

Database testing is the process of validating backend data stored in databases to ensure it is accurate, consistent, secure, and aligned with business rules. It focuses on checking whether data inserted through UI, APIs, or batch jobs is correctly stored, updated, retrieved, and deleted.

In service-based IT companies like Cognizant, projects deal with large enterprise databases across domains such as banking, healthcare, insurance, and retail. That’s why cognizant database testing interview questions are a key part of QA and testing interviews.

Why Database Testing Is Important in Cognizant Projects

To validate UI/API data vs database records
To ensure business rules are enforced at DB level
To prevent data loss, duplication, or corruption
To maintain audit trails and transaction accuracy

Step-by-Step Database Testing Workflow

1. Understand Business Requirements

What data is created or updated?
Which fields are mandatory?
What calculations happen in the database?

2. Schema & Table Validation

Table and column names
Data types and lengths
Default values

3. Constraint Validation

Primary Key
Foreign Key
NOT NULL
UNIQUE

4. CRUD Validation

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

5. Advanced Database Validation

Indexes (performance)
Stored Procedures (business logic)
Triggers (audit & logging)
Transactions (commit/rollback)

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

Basic Database Testing Interview Questions (1–20)

1. What is database testing?

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

2. Why is database testing important in Cognizant projects?

Because Cognizant works on enterprise-scale applications where data accuracy directly impacts business decisions.

3. What skills are required for database testing?

SQL knowledge
Understanding of database concepts
Business logic understanding

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 establishes a relationship between two tables.

7. What is data integrity?

Ensuring data accuracy and consistency across tables.

8. What is normalization?

Reducing data redundancy.

9. What is denormalization?

Adding redundancy for performance.

10. What is a schema?

A logical container for database objects.

SQL Interview Questions for Testing (21–45)

21. Fetch all records from a table

SELECT * FROM users;

22. Fetch users with age greater than 30

SELECT * FROM users WHERE age > 30;

23. Fetch unique city names

SELECT DISTINCT city FROM customers;

24. Sort records by creation date

SELECT * FROM orders ORDER BY created_date DESC;

25. What is GROUP BY?

Groups rows with the same values.

SELECT department, COUNT(*)

FROM employees

GROUP BY department;

26. What is HAVING?

Filters grouped data.

SELECT department, COUNT(*)

FROM employees

GROUP BY department

HAVING COUNT(*) > 5;

27. Difference between WHERE and HAVING?

WHERE	HAVING
Filters rows	Filters grouped data
Used before GROUP BY	Used after GROUP BY

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

46. What is a JOIN?

Used to retrieve 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 use case

Find records without matching data.

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;

Indexes, Stored Procedures & Triggers (66–85)

66. What is an index?

Improves query performance by reducing table scans.

67. Types of indexes

Clustered
Non-clustered
Composite

68. How do testers validate index usage?

By checking execution plans using EXPLAIN.

69. What is a stored procedure?

Pre-compiled SQL code stored in the database.

70. Stored procedure example

CREATE PROCEDURE getUser(IN uid INT)

BEGIN

SELECT * FROM users WHERE id = uid;

END;

71. How do testers test stored procedures?

Input validation
Output verification
Error handling

72. What is a trigger?

Automatically executes SQL on INSERT/UPDATE/DELETE.

73. Trigger example

CREATE TRIGGER audit_update

AFTER UPDATE ON orders

FOR EACH ROW

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

Scenario Based Database Testing Interview Questions (86–110)

86. Scenario: Validate user registration

Record inserted
Default values assigned

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

87. Scenario: Validate update operation

SELECT address FROM users WHERE id=101;

88. Scenario: Validate soft delete

SELECT * FROM users WHERE is_active=’N’;

89. Scenario: Detect duplicate records

SELECT email, COUNT(*)

FROM users

GROUP BY email

HAVING COUNT(*) > 1;

90. Scenario: Validate banking transaction

Debit entry
Credit entry
Balance updated

SELECT balance FROM accounts WHERE acc_id=101;

91. Scenario: Validate rollback

Force failure
Ensure no partial data saved

Advanced Database Testing Interview Questions (111–130)

111. What is a transaction?

A group of SQL statements executed as a single unit.

112. What are ACID properties?

Atomicity
Consistency
Isolation
Durability

113. What is a deadlock?

Two transactions waiting indefinitely for each other.

114. What is isolation level?

Controls visibility of uncommitted data.

115. What is data migration testing?

Validating data accuracy after migration.

Real-Time Use Cases in Cognizant Projects

🏦 Banking

Transaction accuracy
Balance calculation
Audit log validation

🏥 Healthcare

Patient data integrity
Medical history consistency
Compliance checks

🛒 E-commerce

Order vs payment reconciliation
Inventory updates
Refund processing validation

Common Mistakes Testers Make

Validating only UI data
Ignoring NULL and default values
Skipping rollback scenarios
Missing negative test cases
Not validating performance

Quick Revision Sheet

✔ SELECT, WHERE, ORDER BY
✔ JOIN types
✔ GROUP BY, HAVING
✔ CRUD operations
✔ Index basics
✔ Stored procedures
✔ Triggers
✔ Transactions

FAQs – Cognizant Database Testing Interview Questions

Q1. Is SQL mandatory for Cognizant testing interviews?
Yes, SQL is a core requirement.

Q2. Are scenario-based questions common?
Yes, scenario based database testing questions with answers are frequently asked.

Q3. Which databases are commonly used?
Oracle, MySQL, SQL Server, PostgreSQL.