Structured Query Language (SQL) is a straightforward subject,

SQL REFERENCE

Structured Query Language (SQL) is a straightforward subject, partly because

it doesn't do much, and partly because the language is standardized. Most

modern databases use a variant of SQL that, for the most part, conforms to the

American National Standards Institute (ANSI) 92 standard. That standard

means you can use similar, although not quite identical, SQL code to access

many different databases. Fortunately, for basic operations, there's no

difference between most common databases.

SQL lets you perform four basic operations:

§ SELECT - Retrieve data

§ INSERT - Add data

§ UPDATE - Change data

§ DELETE - Remove data