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.

For experienced Selenium testers, database testing becomes extremely important because Selenium automation often validates UI flows, while SQL validation confirms that the UI actions actually impact the database correctly.

In interviews, database questions asked for experience in selenium testing interview are used to check whether a candidate can:

• Validate UI + DB together
  
• Write SQL queries confidently
  
• Debug automation failures caused by incorrect data
  
• Handle real-time data scenarios
  

Why Database Testing Is Important for Experienced Selenium Testers

• UI automation alone is not enough
  
• Backend issues often cause test failures
  
• Enterprise projects require end-to-end validation (UI + DB)
  
• Testers are expected to validate business logic at DB level

Step-by-Step DB Testing Workflow

1. Understand Business Flow

• What UI action creates data?
  
• Which tables are affected?
  
• What backend calculations occur?
  

2. Schema & Table Validation

• Table names and columns
  
• Data types and lengths
  
• Default values
  

3. Constraint Validation

• Primary Key
  
• Foreign Key
  
• NOT NULL
  
• UNIQUE
  

4. CRUD Validation (UI → DB)

Operation	UI Action	SQL Used
Create	Form submit	INSERT
Read	Search/view	SELECT
Update	Edit action	UPDATE
Delete	Delete/Deactivate	DELETE

5. Advanced Validation

• JOIN checks
  
• Stored procedures & triggers
  
• Index & performance
  
• Transaction & rollback
  

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Database Questions Asked for Experience in Selenium Testing Interview (100+ Q&A)

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Basic Database Questions for Experienced Selenium Testers (1–20)

1. Why are database questions asked in Selenium interviews?

Because Selenium validates UI, while databases validate actual data changes.

2. What is database testing?

Validating backend data using SQL queries.

3. How is database testing related to Selenium?

Selenium triggers actions; SQL verifies results.

4. What is CRUD?

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

5. What is a primary key?

A unique identifier for each row.

6. What is a foreign key?

A column that links two tables.

7. What is data integrity?

Accuracy and consistency of data.

8. What is normalization?

Reducing redundancy.

9. What is denormalization?

Adding redundancy for performance.

10. What is a schema?

A logical container for DB objects.

11. What is NULL?

Represents missing data.

12. What is a constraint?

Rules applied to table columns.

13. Types of constraints?

PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL.

14. What is a view?

A virtual table created using SQL.

15. What is an index?

Improves query performance.

16. Difference between UI testing and DB testing?

UI checks frontend; DB checks backend.

17. Can Selenium directly validate DB?

No, SQL queries are required.

18. What DBs are commonly used?

Oracle, MySQL, SQL Server, PostgreSQL.

19. What is data validation?

Ensuring data matches business rules.

20. What is backend validation?

Validating data after UI actions.

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SQL Interview Questions for Testing (21–45)

21. Fetch all records

SELECT * FROM users;

22. Fetch users created today

SELECT * FROM users WHERE created_date = CURRENT_DATE;

23. Fetch users older than 30

SELECT * FROM users WHERE age > 30;

24. Fetch unique city names

SELECT DISTINCT city FROM customers;

25. Sort records by date

SELECT * FROM orders ORDER BY created_date DESC;

26. Count total records

SELECT COUNT(*) FROM orders;

27. What is GROUP BY?

Groups rows with same values.

SELECT status, COUNT(*)

FROM orders

GROUP BY status;

28. What is HAVING?

Filters grouped data.

SELECT status, COUNT(*)

FROM orders

GROUP BY status

HAVING COUNT(*) > 10;

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 payments 

WHERE amount BETWEEN 500 AND 5000;

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JOIN-Based Database Questions (46–65)

46. What is a JOIN?

Combines data from multiple tables.

47. Types of JOINs

• INNER
  
• LEFT
  
• RIGHT
  
• FULL
  

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 without orders

SELECT c.id

FROM customers c

LEFT JOIN orders o

ON c.id = o.customer_id

WHERE o.id IS NULL;

51. Why JOINs are important for Selenium testers?

To validate multi-table data created via UI.

52. What is a self JOIN?

Joining a table with itself.

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Indexes, Stored Procedures & Triggers (66–85)

66. What is an index?

Improves query performance.

67. Why should Selenium testers know indexes?

To debug slow automation executions.

68. What is a stored procedure?

Pre-compiled SQL logic stored in DB.

69. Stored procedure example

CREATE PROCEDURE getOrder(IN oid INT)

BEGIN

  SELECT * FROM orders WHERE id = oid;

END;

70. How do testers validate stored procedures?

• Input
  
• Output
  
• Error handling
  

71. What is a trigger?

Auto-executed SQL on data changes.

72. Trigger example

CREATE TRIGGER audit_insert

AFTER INSERT ON orders

FOR EACH ROW

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

73. Why triggers are tested?

To validate audit and logging logic.

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Scenario Based Database Questions for Experienced Selenium Testers (86–110)

86. Scenario: User registration via UI

• UI submits form
  
• DB record created
  

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

87. Scenario: Update profile via UI

SELECT phone FROM users WHERE id=101;

88. Scenario: Delete user via UI

SELECT * FROM users WHERE id=101;

89. Scenario: Soft delete validation

SELECT * FROM users WHERE is_active=’N’;

90. Scenario: Duplicate record issue

SELECT email, COUNT(*)

FROM users

GROUP BY email

HAVING COUNT(*) > 1;

91. Scenario: Order & payment validation

SELECT o.id, p.amount

FROM orders o

JOIN payments p

ON o.id = p.order_id;

92. Scenario: Rollback on failure

• UI fails
  
• No DB insert should happen
  

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Advanced Database Questions (111–130)

111. What is a transaction?

Group of SQL statements executed as one unit.

112. What are ACID properties?

• Atomicity
  
• Consistency
  
• Isolation
  
• Durability
  

113. What is a deadlock?

Two transactions waiting for each other.

114. What is isolation level?

Controls data visibility.

115. What is data migration testing?

Validating data after migration.

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Real-Time Use Cases for Selenium + Database Testing

🏦 Banking

• UI fund transfer → DB balance validation
  
• Transaction history verification
  

🏥 Healthcare

• Patient registration → DB integrity
  
• Medical history updates
  

🛒 E-commerce

• Order placement → payment mapping
  
• Inventory updates
  

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Common Mistakes Experienced Selenium Testers Make

• Validating only UI, ignoring DB
  
• Writing incorrect JOIN queries
  
• Ignoring rollback scenarios
  
• Missing audit/log tables
  
• Assuming test failures are UI issues
  

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Quick Revision Sheet

✔ SELECT, WHERE, ORDER BY
✔ JOIN types
✔ GROUP BY, HAVING
✔ CRUD validation
✔ Stored procedures
✔ Triggers
✔ Transactions

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FAQs – Database Questions Asked for Experience in Selenium Testing Interview

Q1. Are database questions mandatory for experienced Selenium roles?
Yes, backend validation is expected.

Q2. How much SQL should an experienced Selenium tester know?
SELECT, JOIN, GROUP BY, HAVING, subqueries.

Q3. Are scenario-based DB questions common?
Yes, real time SQL validation interview questions are very common.