Sunday, 29 December 2013

25 Database Testing Interview Questions that Employers ask to judge you.

First of all, What is Database Testing ?

Databases may not deal with the same type of data every time i.e. databases may be heterogeneous. As a result, many kinds of implementation and integration errors may occur in large database systems. These will negatively affect the system's performance, reliability, consistency and security. Thus, it is important to test in order to obtain a database system which satisfies the ACID properties (Atomicity, Consistency, Isolation, and Durability) of a database management system.

Database testing usually consists of a layered process, including the user interface (UI) layer, the business layer, the data access layer and the database itself. 

  • The UI layer deals with the interface design of the database.
  • The business layer includes databases supporting business strategies.
  • The data access layer is the most critical layer. This layer deals with databases directly during the communication process. Database testing mainly takes place at this layer and involves testing strategies such as quality control and quality assurance of the product databases. 

Testing at these different layers is frequently used to maintain consistency of database systems, most commonly seen in the following examples: 

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1. Data is critical from a business point of view. Companies such as Google or Symantec, who are associated with data storage, need to have a durable and consistent database system. If database operations such as insert, delete, and update are performed without testing the database for consistency first, the company risks a crash of the entire system. 

2. Some companies have different types of databases, and also different goals and missions. In order to achieve a level of functionality to meet said goals, they need to test their database system. 

3. The current approach of testing may not be sufficient in which developers formally test the databases. However, this approach is not sufficiently effective since database developers are likely to slow down the testing process due to communication gaps. A separate database testing team seems advisable. 

4. Database testing mainly deals with finding errors in the databases so as to eliminate them. This will improve the quality of the database or web-based system. 

5. Database testing should be distinguished from strategies to deal with other problems such as database crashes, broken insertions, deletions or updates. Here, database refactoring is an evolutionary technique that may apply. 

25 Database Testing Interview Questions that Employers will ask to judge you.

1)      What is data-base testing? 

Data base testing is segmented into four different categories. 
•Testing of Data Integrity 
•Testing of Data Validity 
•Data base related performance 
•Testing of functions, procedure and triggers 

plus the points mentioned above.

2)      In database testing, what do we need to check normally? 

Normally, the things that we check in database testing are: 
•Constraint Check 
•Validation of a Field size 
•Stored procedure 
•Matching application field size to database 
•Indexes for performance based issues 

3)      Explain what is data driven test? 

In a data-table, to test the multi numbers of data, data-driven test is used.  By using this it can easily replace the parameters at the same time from different locations. 

4)      What are joins and mention different types of joins? 

Join is used to display two or more than two table and the types of joins are: 
•Natural Join 
•Inner Join 
•Outer Join 
•Cross Join 

The outer join is divided again in two: 

•Left outer join 
•Right outer join 

5)      What are indexes and mention different types of indexes? 

Indexes are database objects and they are created on columns. To fetch data quickly they are frequently accessed. Different types of indexes are: 
•B-Tree index 
•Bitmap index 
•Clustered index 
•Covering index 
•Non-unique index 
•Unique index 

6)      While testing stored procedures what are the steps does a tester takes? 

The tester will check the standard format of the stored procedures and also it checks the fields are correct like updates, joins, indexes, deletions as mentioned in the stored procedure. 

7)      How would you know for database testing, whether trigger is fired or not? 

On querying the common audit log you would know, whether, a trigger is fired or not. It is in audit log where you can see the triggers fired. 

8)      In data base testing, what are the steps to test data loading? 

Following steps need to follow to test data loading 
•Source data should be known 
•Target data should be known 
•Compatibility of source and target should be checked 
•In SQL Enterprise manager, run the DTS package after opening the corresponding DTS package 
•You have to compare the columns  of target and data source 
•Number of rows of target and source should be checked 
•After updating data in the source, check whether the changes appears in the target or not. 
•Check NULLs and junk characters 

9)      Without using Database Checkpoints, how you test a SQL Query in QTP? 

By writing scripting procedure in VBScript, we can connect to database and can test the queries and database. 

10)   Explain how to use SQL queries in QTP ? 

In QTP using output database check point and database check, you have to select the SQL manual queries option. After selecting the manual queries option, enter the “select” queries to fetch the data in the database and then compare the expected and actual. 

11)   What is the way of writing testcases for database testing? 

Writing a testcases is like functional testing. First you have to know the functional requirement of the application. Then you have to decide the parameters for writing testcases like 
•Objective: Write the objective that you would like to test 
•Input method: Write the method of action or input you want to execute 
•Expected: how it should appear in the database 

12)    To manage and manipulate the test table what are the SQL statements that you have used in Database testing? 

The statements like SELECT, INSERT, UPDATE, DELETE are used to manipulate the table, while ALTER TABLE, CREATE TABLE and DELETE TABLE are used to manage table. 

13)   How to test database procedures and triggers? 

To test database procedures and triggers, input and output parameters must be known. EXEC statement can be used to run the procedure and examine the behaviour of the tables. 
•Open the database project in solution explorer 
•Now in View menu, click the database schema 
•Open the project folder from schema View menu 
•Right click on the object that has to be tested, and then click on the dialog box that says Create Unit Tests 
•After that create a new language test project 
•Select either a) Insert the unit test or b) Create a new test and then click OK 
•Project that has to be configured will be done by clicking on the Project Configuration dialog box. 
•Once it configured click on OK 

14)   How you can write testcases from requirements and do the requirements represents exact functionality of AUT (Application Under Test)? 

To write a testcases from requirements, you need to analyse the requirements thoroughly in terms of functionality. Thereafter you think about the appropriate testcases design techniques like Equivalence partitioning, Black box design, Cause effect graphing etc. for writing the testcases. 
 Yes, the requirements represent exact functionality of AUT. 

15)    What is DBMS? 

DBMS stand for Database management system, there are different types of DBMS 
•Network Model 
•Hierarchical Model 
•Relational Model 

16)   What is DML? 

DML stands for Data Manipulation Language, It is used to manage data with schema objects. It is a subset of SQL. 

17)   What are DCL commands? What are the two types of commands used by DCL? 

DCL stands for Data Control Language, it is used to control data. 

The two types of DCL Commands are: 

Grant: By using this command user can access privilege to database 

Revoke: By using this command user cannot access the database 

18)   What is white box testing and black box testing? 

Black box testing means testing the software for the outputs on giving particular inputs.  This testing is usually performed to see if the software meets the user’s requirements.  There is no specific functional output expected for running this test. 

The white box testing is done to check the accuracy of code and logic of the program.  This testing is done by the programmer who knows the logical flow of the system. 

19)   How does QTP evaluate test results? 

Once the testing is done, QTP will generate a report.  This report will show the checkpoints, system message and error that were detected while testing.  The test results window will show any mismatches encountered at the checkpoints. 

20)   Explain the QTP testing process? 
•QTP testing process is based on following steps: 
•Creating GUI (Graphical User Interface) Map files : Identifies the GUI object which has to be tested 
•Creating test scripts:  Test scripts are recorded 
•Debug tests: Test should be debugged 
•Run tests: Testcases should be run. 
•View results: The results reflects the success or failure of the tests 
•Report detects: If the test is failed, the reasons will be recorded in the report detect file 

21)   What is load testing and give some examples of it? 

To measure the system response, load testing is done.  If the load exceeds the users pattern it is known as stress testing.  Examples of load testing are downloading the set of large files, executing multiple applications on a single computer, subjecting a server to large number of e-mails and allotting many tasks to a printer one after another. 

22)   How to test database manually? 

Testing the database manually involves checking the data at the back end and to see whether the addition of data in front end is affecting the back end or not, and same for delete, update, insert etc. 

23)   What RDBMS stands for and what are the important RDMBS that SQL use? 

RDBMS stands for Relational Database Management Systems that use SQL, and the important RDBMS that SQL uses are Sybase, Oracle, Access ,Ingres, Microsoft SQL server etc. 

24)   What is performance testing and what are the bottlenecks of performance testing? 

Performance testing determines the speed of the computer system performance. It includes the quantitative tests like response time measurement. The problem in performance testing is that you always need a well-trained and experienced man power also the tools you use are expensive. 

25)   What is DDL and what are their commands? 

To define database structure, DDL is used.  DDL stands for Data Definition Language.  The various DDL commands include Create, Truncate, Drop, Alter, Comment and Rename

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