Introduction

SQL is an essential skill that every database developer should have. It is a universal language that is used to manage, manipulate and query databases. Employers also seek candidates who have robust SQL knowledge, which makes it a top interview question for database developers. In this article, we will be discussing the top SQL interview questions that can help you prepare for your next interview.

Top SQL Interview Questions

1. What is SQL?

This question may seem easy, but a lot of interviewees fail to explain what SQL means. SQL stands for Structured Query Language, which is used in relational database management systems to communicate with databases. SQL is a declarative language that describes the task but not how to carry it out. SQL has four main components: Data Definition Language (DDL), Data Manipulation Language(DML), Data Control Language(DCL), and Transaction Control Language.

2. What is the difference between a Primary Key and a Unique Key?

Both primary and unique keys are used to enforce data integrity in a database. A primary key is a column that uniquely identifies each row in a table. A table can have only one primary key, and it cannot contain null values. A unique key is used to ensure that no two rows in a table have the same values in a particular column or a combination of columns. A table can have multiple unique keys, and unlike a primary key, it can contain null values.

3. What is a Stored Procedure?

A stored procedure is a pre-defined SQL code that is stored in the database. Stored procedures are beneficial because they allow for modular programming and reduce network traffic. They are also used to improve performance because stored procedures are compiled and optimized by the database server. Stored procedures can accept parameters, which makes them more flexible compared to regular SQL queries.

Conclusion

SQL interview questions are designed to test the basic SQL knowledge and problem-solving skills of database developers. The questions outlined in this article are just a few of the many possible interview questions you may encounter. It is important to note that a comprehensive understanding of SQL is necessary to excel in database development. Keep practicing and learning, and you will succeed in your quest for a SQL-related career.