SQL Introduction

This page contains a brief introduction to SQL.

About SQL

SQL stands for Structured Query Language.

SQL is a language that enables you to work with a database. Using SQL, you can insert records, update records, and delete records. You can also create new database objects such as databases and tables. And you can drop (delete) them.

More advanced features include creating stored procedures (self contained scripts), views (pre-made queries), and setting permissions on database objects (such as tables, stored procedures, and views).

Although SQL is an ANSI (American National Standards Institute) standard, there are many different versions of SQL. Different database vendors have their own variations of the language.

Having said this, to be in compliance with the ANSI standard, they need to at least support the major commands such as DELETE, INSERT, UPDATE, WHERE etc. Also, you will find that many vendors have their own extensions to the language — features that are only supported in their database system.

Furthermore, transact-SQL is an extension to the ANSI standard and provides extra functionality.

Using SQL

To run the SQL queries in this tutorial, you will need a database management system such as MySQL, Oracle, Microsoft Access, SQL Server, etc.

If you're not familiar with database management systems, check out my Microsoft Access tutorial, my SQL Server tutorial, and my MySQL tutorial.

If you need to build a website with a database providing the content, you will generally need knowledge of the following:

  • A server side scripting language (i.e. ColdFusion, PHP, ASP/.NET)
  • A database query language (eg, SQL)
  • A client side markup language and style sheets (eg, HTML/CSS)

Although SQL can be quite involved, you can achieve a lot with a handful of SQL statements. When using SQL on a website, you will often find yourself either selecting a record, inserting a record, updating a record, or deleting a record. Fortunately, SQL has commands for performing each of these actions.

The next lesson covers the SQL syntax basics.