SQL injection attack can access the sensitive data from the database. The attacker can Insert, Update, Delete and execute the administration operation.

Detection:

Authentication Forms : When user enter the web form, chances are that the user credentials are checked against the database.

Search Engines: String entered and submit by the user in SQL query that extracts all records from database.

E-Commerce Site: The Products Storage in database . Tester have to manage the list of all input values used in SQL query that extracts all relevant records from the database.

First Test: Single quote (') or semicolon (;) to the filed or parameter added under test. The first is used in SQL as a string termination and if not filtered by the application.

Second Test: Used to end the SQL statement and if its not filtered.

TESTING EXAMPLE :
SELECT
FROM TBLUSER
WHERE TBL_USER='Name' AND TBL_PASSWORD='PASSWORD'
If user enter
TBL_USER=1
TBL_PASSWORD=1
If parameters are sent through GET method on sever, we notice that system has authenticated the user without knowing the name and password because query return condition true value (OR 1=1).

Fingerprinting The Database

On moving to advance SQL injection exploitation tester need to know the backend.
Example:
Backend Error

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '\'' at line 1