RE-TESTING: we check for the particular bug and its
dependencies after it is said to be fixed.
REGRESSION TESTING : We check the entire system whether the
fixed bug make any adverse effect in the existing system or not.
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Retesting means we are going to check weather the bug is
fixed or not..
Regression testing means after getting confirmation the bug is fixed we are going to check the fixation is going to create any problems in the application or not.. that means due to the fixation of the bug we got any side effects in the application or not.
Retesting & regression testing:
retesting: retesting is conduct to test different combinations of data i.e called retesting
regression testing:regression testing once the tester report the bug after the developer resolve the bug and developer should assign the build to tester after the test engineer should test thebuild the modifying build is working or not this process called Regression Testing.
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RE-TESTING: we check for the particular bug and its dependencies after it is said to be fixed.

REGRESSION TESTING: We check the entire system whether the fixed bug make any adverse effect in the existing system or not.

select max(column name) from table name where column name !=(SELECT max (column name) FROM Table name)

select max(Salary) from Employee where Salary <>(SELECT max (Salary) FROM Employee)

V- Model

http://www.surfersjunkyard.com/Software_Testing_/Testing_Methodology/V_Testing_Model/v_testing_model.html