DATABASE TESTING

Data base testing materials with real time scenarios:

Basics of Database testing contains the following:

1. How to connect to the database?

2. Ability to write simple queries to retrieve data and manipulate the data using DML operations.

3. Functional flow should be very well known!

4. Good knowledge on table level, column level constraints, ability to understand and execute complex queries related to joins is added advantage.

Data base testing basically include the following. 

1)Data validity testing. 

2)Data Integritity testing 

3)Performance related to database. 

4)Testing of Procedure triggers and functions. 

For doing data validity testing you should be good in SQL queries 

For data integrity testing you should know about referintial integrity and different constraint.

For performance related things you should have idea about the table structure and design. 

For testing Procedure triggers and functions you should be able to understand the same.


This document is to discuss general test specification issues for SQL server back end testing and

to provide testers a test design guide that includes test methodology.

Most systems, i.e. Forecast LRS, Delta, KENAI, KBATS and so on, that are developed by ITG

have client-server architectures. However, only a few projects have their back end completely tested.

1. Why back end testing is so important

2. Characteristics of back end testing

3. Back end testing phases

4. Back end test methods

1. Why back end testing is so important

A back end is the engine of any client/server system. If the back end malfunctions, it may cause system deadlock, data corruption, data loss and bad performance. Many front ends log on to a single SQL server. A bug in a back end may put serious impact on the whole system. Too many bugs in a back end will cost tremendous resources to find and fix bugs and delay the system developments.

It is very likely that many tests in a front end only hit a small portion of a back end. Many bugs in

a back end can not be easily discovered without direct testing.

Back end testing has several advantages: The back end is no longer a "black box" to testers. We have full control of test coverage and depth. Many bugs can be effectively found and fixed in the early development stage. Take Forecast LRS as an example, the number of bugs in a back end was more than 30% of total number of bugs in the project. When back end bugs are fixed, the system quality is dramatically increased.

2. Differences between back end testing and front end testing

It is not easier to understand and verify a back end than a front end because a front end usually
has friendly and intuitive user interfaces.

A back end has its own objects, such as, tables, stored procedures and triggers. Data integrity and protection is critical. Performance and multi-user support are big issues. Slowness in operation can be vital to the project’s future.

There are no sufficient tools for back end testing. SQL language is mainly a testing tool. MS Access and MS Excel can be used to verify data but they are not perfect for testing. However, there are a large number of test tools available for front end testing.

To be able to do back end testing, a tester must have strong background in SQL server and SQL language. It is relatively difficult to find testers who understand both SQL server and SQL testing. This causes a shortage of back end testers.

3. Back end testing phases

There are several phases in back end testing. The first step is to acquire design specifications for an SQL server. The second step is test specification design. The next step is to implement the tests in this design with SQL code. The test specification design should contain information concerning component testing (individual pieces of the system), regression testing (previously known bugs), integration testing (several pieces of the system put together), and then the entire system (which will include both front and back ends).

Component testing will be done early in the development cycle. Integration and system tests (including interfaces to front ends and nightly processes) are performed after the component tests pass. Regression testing will be performed continuously throughout the project until it is finished. The back end
usually does not have an independent beta test, as it only exercised by the front end during the beta test
period. The last step is to deliver users a quality product.

4. Back end test methodolodogy

Back end test methodology has many things in common with front end testing and API testing. Many test methods can be used for back end testing. Structural testing and functional testing are more effective approaches in back end testing. They are overlapped in some test cases. However, the two methods may discover different bugs. We strongly recommend testers to do both types of testing.
There are many other test methods that can be applied to back end testing. We list a few below.
For other test methods, please check other test design references.

Structural testing:

A back end can be broken down into a finite number of testable pieces based on a back end’s

structure. Tests will verify each and every object in a type of structure.

Functional testing:

A back end can be broken down into a finite number of testable pieces based on application’s functionality. The test focus is on functionality of input and output but not on the implementation and structure. Different projects may have different ways to break down.

Boundary testing:
Many columns have boundary conditions. For example, in a column for percentages, the value can not be less than zero and can not be greater than 100%. We should find out these types of boundary conditions and test them.

Stress testing:
It involves subjecting a database to heavy loads. For incidence, many users heavily access the same table that has a large number of records. To simulate this situation, we need to start as many machines as possible and run the tests over and over.