Structured Query Language, also known as SQL, is a query and programming language. It can be used for accessing, updating, deleting, and adding data in a database. SQL can also be used for managing the RDBMS (Relational Database Management System) itself. Different databases may use versions of SQL that very slightly, but most comply with the standard ANSI SQL-92 implementation of SQL, commonly call ANSI SQL. You can group SQL statements into two main categories: Data Definition Language (or DDL) and Data Manipulation Language (or DML).
DDL statements, as the name suggests, allow you to define the database structure. Most DDL statements begin with CREATE, ALTER, or DROP. The two DDL statements we are going to cover today are CREATE DATABASE (used for creating new databases) and ALTER DATABASE (used for altering existing databases). We will look at the exact syntax of these two statements later on in this article.
DML statements, on the other hand, are used for manipulating the data inside database objects. For example, the SELECT statement allows you to query the data inside a database, the INSERT statement allows for the addition of new data, the UPDATE statement updates selected data, and the DELETE statement allows you to remove data. As this series progresses we will cover these statements as well as many more DDL and DML statements in greater detail.
We now know what SQL is, but what is T-SQL? Simply, T-SQL is SQL Server’s enhanced version of the standard SQL programming language. T-SQL in SQL Server 2000 allows for such things as stored procedures, IF and WHILE statements, and additional functions/data types (we will cover data types when we start creating tables) that are not available in standard SQL.