Structured Query Language

Structured Query Language (SQL) is a widely-used programming language for working with relational databases. The name of the language is generally pronounced as the three letters of its abbreviation ˈɛs kjuː ˈɛl or, in some people's usage, as ˈsiːkwəl.

This Wikibook provides a short description of SQL, its origins, basic concepts and components, and many examples. The book follows the specifications of the SQL:2011 standard developed by a common committee of ISO and IEC. Their publications are not freely available but can be ordered online. Or you may want to refer to a working draft that you can download from Whitemarsh Information Systems Corporation.

Introduction

About the Book

Database Management Systems (DBMS)

Relational DBMS (rDBMS)

SQL: A Language for Working with rDBMS

SQL: The Standard ISO IEC 9075 and various Implementations

Language Elements

Learning by Doing

The Snippets Corner

SELECT code FROM examples WHERE topic = ...

Foundation

Create a simple Table

Handle Data

Example Database Structure

Example Database Data

Data Query Language

SELECT Fundamentals

Join Operation

Grouping

IS NULL Predicate

Predefined Functions

Set Operations

Case Expression

Subquery

Views

Data Manipulation Language

INSERT

INSERT, using Subqueries

UPDATE

UPDATE, using Subqueries

DELETE

DELETE, using Subqueries

MERGE

TRUNCATE

COMMIT and ROLLBACK

Data Definition Language

CREATE TABLE

Data Types

Foreign Key

Alter Table

Drop Table

Temporary Table

Indexes

Data Control Language

Managing Rights (GRANT / REVOKE)

Advanced Topics

Additional SELECT features

Pattern Matching (LIKE Predicate and much more)

IN, SOME/ANY, ALL, EXISTS

Advanced Grouping: Rollup / Cube

Window functions (Data Warehouses, OLAP)

With Clause (Common Table Expression CTE)

Recursions

NULLs and the Three Valued Logic

Transactions / Isolation Levels

Some Notes on typical SQL (non-trivial) Tasks

Retrieve Top N Rows per Group

Eliminate Duplicates

Appendices

Warnings and Exceptions (SQLSTATE)

Glossary

See also

• Wikibook Microsoft SQL Server
• Wikibook MySQL
• Wikibook Oracle Database
• Wikibook PostgreSQL
• Wikibook SQLite
• Wikipedia: SQL Key Words