SQL Tutorial
SQL is a standard language for storing, manipulating, and retrieving data in databases.
Our SQL tutorial will teach you how to use SQL in MySQL, SQL Server, MS Access, Oracle, Sybase, Informix, Postgres, and other database systems.
Examples in Each Chapter
With our online SQL editor, you can edit the SQL statements, and click on a button to view the result.

Example

SELECT * FROM Customers;
Try it Yourself »

Click on the "Try it Yourself" button to see how it works.

Introduction to SQL

SQL is a standard language for accessing and manipulating databases.

What is SQL?

SQL stands for Structured Query Language

SQL lets you access and manipulates databases

SQL became a standard of the American National Standards Institute (ANSI) in 1986 and of the International Organization for Standardization (ISO) in 1987

What Can SQL do?

SQL can execute queries against a database

SQL can retrieve data from a database

SQL can insert records into a database

SQL can update records in a database

SQL can delete records from a database

SQL can create new databases

SQL can create new tables in a database

SQL can create stored procedures in a database

SQL can create views in a database

SQL can set permissions on tables, procedures, and views

SQL is a Standard - BUT...

Although SQL is an ANSI/ISO standard, there are different versions of the SQL language.

However, to be compliant with the ANSI standard, they all support at least the major commands (such as SELECT, UPDATE, DELETE, INSERT, WHERE) in a similar manner.

Note: Most of the SQL database programs also have their own proprietary extensions in addition to the SQL standard!

Using SQL in Your WebSite

To build a website that shows data from a database, you will need:

An RDBMS database program (i.e. MS Access, SQL Server, MySQL)

To use a server-side scripting language, like PHP or ASP

To use SQL to get the data you want

To use HTML / CSS to style the page

RDBMS

RDBMS stands for Relational Database Management System.

RDBMS is the basis for SQL, and for all modern database systems such as MS SQL Server, IBM DB2, Oracle, MySQL, and Microsoft Access.

The data in RDBMS is stored in database objects called tables. A table is a collection of related data entries and it consists of columns and rows.

Look at the "Customers" table:

Every table is broken up into smaller entities called fields. The fields in the Customers table consist of CustomerID, CustomerName, ContactName, Address, City, PostalCode, and Country. A field is a column in a table that is designed to maintain specific information about every record in the table.

A record, also called a row, is each individual entry that exists in a table. For example, there are 91 records in the above Customers table. A record is a horizontal entity in a table.

A column is a vertical entity in a table that contains all information associated with a specific field in a table.