Frequently asked SQL interview questions in an interview and their best answers

With the increase in number of software companies there is a parallel increase in the competition too and this is why suggestion for SQL interview questions and answers is necessary before appearing for an interview. Below are the list of common questions and answers asked by the interviewers.

Frequently asked SQL interview questions and answers

SQL Queries interview

What is Database Management System?

This is one of the fundamental SQL interview questions asked by the interviewer to a fresher as well as an experienced candidate. The system is a precise collection of language based programs that users can use for storage, retrieval, updating and deletion of data and information in a database.

What do you mean by RDBMS?

The second most favorite among the SQL interview questions is about RDBMS. Relational Database Management System is all about a relational model based system where data can be accessed or assembled again by following different paths without reorganization of the tables in the database. It can be done with the help of API and SQL.

What are the types of SQL statements?

This is a question that normally a fresher faces in an interview. There are three types of SQL statements.

  • Data Definition Language (DDL) is particularly used to signify the structure that stores the data like Truncate Table, Drop, Alter or Create.
  • Data Manipulation Language (DML) is used to manipulate data with different type of operations like Delete, Insert, Update, etc.
  • Data Control Language (DCL) is the part of the language that is used to control data visibility by setting privileges, granting access and many other related functions.

What are the basic advantages of the language?

The language is very sophisticated yet easy to learn. It is also used worldwide for major programming ventures by the users. It is also a versatile language that can easily interact with other languages like ORACLE and MYSQL. The language has simple English words to define the functions with which complex operations can be done very conveniently.

What are the properties of Database Transactions?

This is a very common question asked by the interviewer. The properties are commonly termed as ‘ACID’ due to the abbreviations of the first letters.

  • Atomicity

The steps that build a transaction are reflected in the database when perfectly completed and compiled. Is any single step fails to comply then the entire transaction is set back.

  • Consistency

If the transaction succeeds then the state of the database will move from one state to another but when it fails it retains its previous original state.

  • Isolation

Every single transaction operates like a single entity in the entire system.

  • Durability

After the successful completion of the transaction the updates records and rows should be available for all other future transactions permanently.

Structured Query Language (SQL) is the database communication based language that is standardized as per American national Standards Institute (ANSI). This language is widely used in Database Management System program development. SQL interview questions are based on basic concepts about the language and its implementation that are asked to an interviewee to judge his or her depth in the particular field.

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