SQL

The databases that use the SQL syntax are called Relational databases. Popular examples are:

Relational databases use SQL to read, create, update and delete data.

The name comes from the way that data is stored in multiple, related tables. Within the tables, data is stored in rows and columns.

What is SQL?

SQL stands for Structured Query Language, as it is the special purpose language for querying data in Relational Databases.

MySQL, PostgreSQL, SQLite all use SQL for querying with slight syntax differences.

Basic SQL commands

Select

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Update

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Delete

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Insert

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Create database

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Drop database

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Create table

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Alter table

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Drop table

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As the name implies, relational databases have related data. In other words, we can join our tables to present these related data together.

(INNER) JOIN

Returns records that have matching values in both tables.
LEFT (OUTER) JOIN

Returns all records from the left table, and the matched records from the right table.
RIGHT (OUTER) JOIN

Returns all records from the right table, and the matched records from the left table.
FULL (OUTER) JOIN

Returns all records when there is a match in either left or right table.