What is SQL?

What is SQL?

SQL stands for Structured Query Language. It is the standard language for storing, manipulating, and retrieving data in a database.

What can SQL do?

• Query data: ask questions like "which customers live in Mexico?"
• Insert new records into tables.
• Update existing records.
• Delete records.
• Create new databases, tables, views, and more.

Where does SQL run?

SQL runs on a database management system (DBMS). Popular ones include:

• MySQL (open source, very popular)
• SQL Server (Microsoft)
• PostgreSQL
• Oracle
• SQLite (embedded, single-file)

Most SQL is the same everywhere, but each system has small differences and extensions.

Rows and columns

Data is stored in tables. A table looks like a spreadsheet:

• Each table has columns (CustomerID, CustomerName, Country).
• Each row is one record (one customer).

SQL is not case-sensitive

SELECT and select mean the same thing. By convention, SQL keywords are written in UPPERCASE.

TL;DR

• SQL is the standard language for working with databases.
• It reads and writes data inside tables of rows and columns.
• Popular databases: MySQL, SQL Server, PostgreSQL, Oracle, SQLite.
• SQL keywords are conventionally written in uppercase.