Database Testing Full Notes PDF For QA

Beginner to Experienced QA Testers

Database Testing Notes For QA: Database Testing means checking whether the data stored in a database is correct, complete, consistent, and secure. These notes cover the important concepts in simple language, with practical examples and interview points.

1. What is Database Testing?

Database Testing is the process of verifying that data is stored, updated, retrieved, and deleted correctly in a database.

Simple example: You register on a website using your name and email address. After registration, a tester checks whether the correct name and email have been saved in the database.

Webvittha.com

2. Why is Database Testing important?

To verify data accuracy.
To ensure no data is missing.
To check that updates are saved correctly.
To identify duplicate records.
To verify relationships between tables.
To ensure data security and access permissions.
To check that the application and database show consistent information.

3. What is a Database?

A database is an organized collection of data that can be stored, accessed, and managed.

For example, an employee database may contain employee IDs, names, email addresses, departments, and salaries.

Important database terms

Term	Simple meaning
Database	Collection of organized data
Table	Data arranged in rows and columns
Row	One complete record
Column	One type of information
Primary Key	Uniquely identifies a record
Foreign Key	Connects related tables
SQL	Language used to communicate with a database
DBMS	Software used to manage databases
Schema	Structure and organization of a database
NULL	Missing or unknown value

4. Types of Database Testing

1. Data Integrity Testing

Checks whether data remains correct and complete.

Example: A customer’s email should not change unless an update is performed.

2. Structural Testing

Checks tables, columns, data types, keys, constraints, and relationships.

Example: Employee ID should be a number or another defined identifier type, as specified by the schema.

3. Functional Database Testing Notes For QA

Checks whether database operations work according to business requirements.

Example: After an employee’s department is changed, the correct department should be stored.

4. Security Testing

Checks permissions and protection of sensitive data.

Example: A regular employee should not be able to view restricted salary records.

5. Performance Testing

Checks how efficiently the database handles queries and large volumes of data.

Example: A report that normally loads in two seconds should not take 30 seconds under expected conditions.

5. CRUD Operations in Database Testing

CRUD stands for Create, Read, Update, and Delete.

Operation	SQL command	Purpose
Create	`INSERT`	Add a record
Read	`SELECT`	Retrieve records
Update	`UPDATE`	Modify a record
Delete	`DELETE`	Remove a record

Example table: Employees

EmployeeID	Name	Department
101	Amit	QA
102	Priya	Development
103	Rahul	Support

6. Important SQL Queries for Testers

SELECT — Read data

SELECT * FROM Employees;

Displays all columns and records in the table.

WHERE — Find specific data

SELECT * FROM EmployeesWHERE EmployeeID = 101;

Returns the employee with ID 101.

INSERT — Add data

INSERT INTO Employees(EmployeeID, Name, Department)VALUES (104, 'Neha', 'QA');

Adds a new employee, assuming the table allows these values.

UPDATE — Modify data

UPDATE EmployeesSET Department = 'Testing'WHERE EmployeeID = 101;

Changes the department for employee 101.

DELETE — Remove data

DELETE FROM EmployeesWHERE EmployeeID = 104;

Deletes employee 104.

Important: Always verify the WHERE condition before running UPDATE or DELETE, particularly in shared or production databases.

7. SQL Concepts You Must Know

Concept	What it does
`ORDER BY`	Sorts query results
`GROUP BY`	Groups records for analysis
`COUNT()`	Counts records
`SUM()`	Adds numeric values
`DISTINCT`	Returns unique values
`LIKE`	Searches using a pattern
`IN`	Matches values in a list
`BETWEEN`	Checks a range
`INNER JOIN`	Returns matching records from both tables
`LEFT JOIN`	Returns all left-table records and matching right-table records
Subquery	A query inside another query
`HAVING`	Filters grouped results

Example — count employees by department:

SELECT Department, COUNT(*)FROM EmployeesGROUP BY Department;

8. Primary Key, Foreign Key and Constraints

Primary Key: Uniquely identifies each record. Duplicate or NULL values are not allowed.
Foreign Key: Maintains a relationship with a key in another table.
Unique: Prevents duplicate values in a column or combination of columns, subject to database rules for NULLs.
NOT NULL: Prevents a column from storing NULL.
CHECK: Restricts values according to a condition.
DEFAULT: Supplies a value when one is not provided and the database rules allow it.

Example: An EmployeeID can be a primary key, while DepartmentID can reference a department table.

Interview point: A foreign key helps prevent invalid references, such as assigning an employee to a department that does not exist, when the relevant constraint is enforced.

9. Database Testing vs UI Testing vs API Testing

Testing type	What you check
UI Testing	What the user sees on the screen
API Testing	Data sent and returned through API requests
Database Testing	What is actually stored in the database

Real-time example: A user changes their email address on a website.

UI testing verifies that the email field accepts the new address.
API testing verifies the update request and response.
Database testing verifies that the correct email is saved and the old value is no longer stored where it should not be.

10. Real-Time Database Testing Scenarios

These are important for both freshers and experienced testers.

Verify that registration data is saved correctly.
Verify that updated information persists after refreshing or reopening the application.
Check whether duplicate email addresses are allowed according to requirements.
Verify that deleting a record produces the expected database result.
Check whether NULL values are accepted in optional and mandatory columns.
Verify primary key and foreign key relationships.
Check whether a failed transaction leaves partial or inconsistent data.
Verify that totals displayed in a report match the database calculation.
Check whether unauthorized users can access restricted records.
Verify that bulk data imports do not skip or duplicate records.
Check that date, time, currency, and decimal values are stored accurately.
Verify that application and database values remain consistent after API operations.

11. Database Testing Interview Questions

1. What is database testing?

2. What is the difference between DELETE, TRUNCATE and DROP?

3. What is the difference between WHERE and HAVING?

4. What is a JOIN?

5. What is data integrity?

6. How do you test whether an update is saved?

7. What is a transaction?

8. What are ACID properties?

9. What is normalization?

10. What is an index?

11. How do you find duplicate records?

12. How do you report a database defect?

12. What should beginners and experienced testers focus on?

For beginners / freshers

Database basics, tables, rows and columns
SELECT, WHERE, INSERT, UPDATE and DELETE
Primary keys, foreign keys and constraints
Basic JOINs and aggregate functions
Simple data validation scenarios

Database Testing Notes For experienced testers

Complex joins, subqueries and query analysis
Transactions, ACID and rollback validation
Data migration and reconciliation
API-to-database and UI-to-database validation
Concurrency, locking and deadlocks
Performance, indexing and execution plans
Security, access control and sensitive data handling

Database Testing Full Notes PDF for QA: Complete Guide for Beginners