SQL Overview

SQL is the language relational databases use for all their activities.

SQL is often divided into two broad categories: Data Definition Language(DDL) and Data Manipulation Language (DML). DDL is used for creating and altering database objects such as tables, views, stored procedures and logins. DML is for selecting, inserting, updating or deleting data.

Anything that can be done in a DBMS can be coded as SQL.

SQL is also embedded in web or Windows (Microsoft, Linux, Mac, etc.)applications that are driven by underlying databases.

Any database professional is expected to be proficient in SQL

SQL is considered a fourth generation language. That means that instead of writing code that tells the computer how to do something, step by step, the way you do with C# or C++, you instead tell the computer what you want to do. It is a "declarative" rather than a "procedural" language.

For a history of SQL look at http://en.wikipedia.org/wiki/SQL