Top 17 SQL Interview Questions and Responses in 2022

SQL can be described as a special-purpose language that interacts with databases. Strong relational databases are a requirement for most applications that use data. SQL allows you to interact with these relational database systems.
Q1. Q1. What is SQL?
SQL stands for Structured Query Language. It is used to interact with databases. SQL is the default query language used to communicate with RDBMS (Relational Database Management Systems). It can also be used for performing various operations on data types that relate to data manipulation. Q2. What are the different commands for SQL?
These are the different SQL commands that you need to know: DDL (Data Definition Language): DDL is used to create the database’s data structure before it is created. It is responsible for creating and restructuring database objects. DDL commands include Create table
Drop table
Alter table
2. DML, Data Manipulation Language: DML is a way to manipulate existing data in a database. It allows users to retrieve and modify this data. DML is used to perform operations such as adding data to a database with the “Insert” command, keeping it up-to-date using the “Update” command, and deleting data from databases using the “Delete” command. DCL, or Data Control Language: DCL controls or restricts access within a database. DCL subsets can be used to create objects that relate to user access and control privilege distribution for authorised users. DCL uses the ‘Grant’ as well as ‘Revoke’ commands. TCL or Transaction Control Language: TCL command help to control the DML commands’ changes. They also authorize statements that allow transactions to be assembled in conjunction with them. TCL commands include ‘Commit’ (or ‘Rollback), ‘Savepoint’ (or ‘Transaction’), ‘Begin’ (or ‘Transaction’). Describe the various database management systems.
There are four main types. Hierarchical Database: This database is structured in the same way as a tree. Data is stored in a hierarchy. This is how you can understand the difference between a parent structure and a child structure. A parent structure can contain many things, while a child structure may only have one parent.
Network Database: This database can be viewed as a graph, where different points can be linked together. It allows multiple relationships to be created between a single child structure.
Relational Database: This database is structured as a table. The values are given in the table.