SQL Introduction

From WikiOD

Remarks[edit | edit source]

SQL is Structured Query Language used to manage data in a relational database system. Different vendors have improved upon the language and have variety of flavors for the language.

NB: This tag refers explicitly to the ISO/ANSI SQL standard; not to any specific implementation of that standard.

Versions[edit | edit source]

Version Short Name Standard Release Date
1986 SQL-86 ANSI X3.135-1986, ISO 9075:1987 1986-01-01
1989 SQL-89 ANSI X3.135-1989, ISO/IEC 9075:1989 1989-01-01
1992 SQL-92 ISO/IEC 9075:1992 1992-01-01
1999 SQL:1999 ISO/IEC 9075:1999 1999-12-16
2003 SQL:2003 ISO/IEC 9075:2003 2003-12-15
2006 SQL:2006 ISO/IEC 9075:2006 2006-06-01
2008 SQL:2008 ISO/IEC 9075:2008 2008-07-15
2011 SQL:2011 ISO/IEC 9075:2011 2011-12-15
2016 SQL:2016 ISO/IEC 9075:2016 2016-12-01

Overview[edit | edit source]

Structured Query Language (SQL) is a special-purpose programming language designed for managing data held in a Relational Database Management System (RDBMS). SQL-like languages can also be used in Relational Data Stream Management Systems (RDSMS), or in "not-only SQL" (NoSQL) databases.

SQL comprises of 3 major sub-languages:

  1. Data Definition Language (DDL): to create and modify the structure of the database;
  2. Data Manipulation Language (DML): to perform Read, Insert, Update and Delete operations on the data of the database;
  3. Data Control Language (DCL): to control the access of the data stored in the database.

SQL article on Wikipedia

The core DML operations are Create, Read, Update and Delete (CRUD for short) which are performed by the statements INSERT, SELECT, UPDATE and DELETE.

There is also a (recently added) MERGE statement which can perform all 3 write operations (INSERT, UPDATE, DELETE).

CRUD article on Wikipedia

Many SQL databases are implemented as client/server systems; the term "SQL server" describes such a database.

At the same time, Microsoft makes a database that is named "SQL Server". While that database speaks a dialect of SQL, information specific to that database is not on topic in this tag but belongs into the SQL Server documentation.