The SQL Language

Structured Query Language (SQL) is the language used to manipulate relational databases. SQL is tied very closely with the relational model.

In the relational model, data is stored in structures called relations or tables. Each table has one or more attributes or columns that describe the table. In relational databases, the table is the fundamental building block of a database application. Tables are used to store data on Employees, Equipment, Materials, Warehouses, Purchase Orders, Customer Orders, etc. Columns in the Employee table, for example, might be Last Name, First Name, Salary, Hire Date, Social Security Number, etc.

SQL statements are issued for the purpose of:

• Data definition - Defining tables and structures in the database (DB).
• Data manipulation - Inserting new data, Updating existing data, Deleting existing data, and Querying the Database ( Retrieving existing data from the database).

Another way to say this is the SQL language is actually made up of 1) the Data Definition Language (DDL) used to create, alter and drop scema objects such as tables and indexes, and 2) The Data Manipulation Language (DML) used to manipulate the data within those schema objects.