Overview of SQL

Structured Query Language (SQL) is used to manipulate, retrieve, insert, update, and delete data in relational database management system (RDBMS). To make it simpler, SQL tells the database what to do and exactly what it needs. SQL is a standard language that all RDBMS systems such as MySQL, MS Access, MS SQL, Oracle, Postgres, and others use.

Using SQL, the user can access, define and manipulate the data from MySQL. We can leverage SQL modules, libraries, and precompilers to embed with the other languages which help in creating/dropping databases and tables, manage view, stored procedures, function etc. in a database. Using SQL, we can also manage permissions on tables, procedures and different views.

The following are a few important SQL commands that we explain in detail later in the chapter:

• SELECT: Extracts data from a database
• UPDATE: Updates data from a database
• DELETE: Removes existing records from a database
• INSERT INTO: Add new information into a database
• CREATE DATABASE: Creates a new database
• ALTER DATABASE: Modifies or change characteristics of a database
• DROP DATABASE: Delete a database
• CREATE TABLE: Creates a new table
• ALTER TABLE: Modifies or change characteristics of a table
• DROP TABLE: Deletes a table
• CREATE INDEX: Creates an index
• DROP INDEX: Remove an index