SQL interview questions for QA Testers

Usually SQL interview questions are no surprise for any QA Tester who spent enough time on QA interview preparation. Almost every Software Quality Assurance Tester done black or white box testing of the software application developed with most popular commercial databases like MS SQL, Oracle SQL or open source databases like MySQL, PostgreSQL. As we all know, relational databases based on the concepts of relational algebra, but QA Tester does not need to comprehend relational algebra to test application developed with relational databases or answer on database interview questions, probably with exception for folks working for companies like Google, Microsoft or Oracle.

If QA Tester indicates on the resume that he or she has the database experience, an interviewer will definitely ask QA Engineer a few common SQL interview questions to determine the depth of the knowledge in database area. Common database interview questions are an extremely easy problems that an interviewer might use to determine whether interviewee have ever used T-SQL,PL/SQL or MySQL before or whether you were tailoring your resume when you mentioned it, while another database interview questions would determine your level of particular database knowledge.

First of all while preparing for database interview, software Tester should cover all the database related terminology, for example you should know the answers on any of these DB interview questions.

• What does RDBMS stand for?
• What do DDL, DML and DCL stand for?
• What is a primary key?
• What is the main role of a primary key in a table?
• What is a foreign key?
• Can a table have more than one foreign key defined?
• What types of joins are possible with database server?
• What's the difference between an inner join and an outer join?
• What is a stored procedure?
• What is trigger?
• What is view?
• What is cursor?

The next set of interview questions could puzzle some unexperienced Quality Assurance Engineers.

• What is difference between DELETE, TRUNCATE and DROP commands?
• Explain the difference between function and stored procedure?
• What is SQL Profiler?
• What default TCP Port is Microsoft SQL Server running under?
• What default TCP Port is Oracle SQL Server running under?
• What default TCP Port is MySQL running under?

Lastly QA Manager may ask a few coding interview questions. The candidate should be prepared to writing some SQL code on a whiteboard. Usually it involves a dialogue about written code, and analysis of SQL code correctness, compatibility and testing.

• How to add record to a table?
• How to add column to a table?
• How do you change value of the field?
• How to remove duplicate rows from a table?
• Write a code to select the last N rows from a table?
• Write a code to select the top N rows from a table?
• Could you implement IF-THEN-ELSE logic in a SELECT statement?

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