SQL (Structured Query Language) is a widely used database language, providing means of data manipulation (store, retrieve, update, delete) and database creation. SQL is an ANSI (American National Standards Institute) standard computer language for accessing and manipulating databases. SQL statements are used to perform tasks such as update data on a database, or retrieve data from a database. Some common relational database management systems that use SQL are: Oracle, Sybase, Microsoft SQL Server, Access, Ingres, MySQL etc. Although most database systems use SQL, most of them also have their own additional proprietary extensions that are usually only used on their system. However, the standard SQL commands such as SELECT, INSERT, UPDATE, DELETE, CREATE, and DROP can be used to accomplish almost everything that one needs to do with a database.

A relational database system contains one or more objects called tables. The data or information for the database is stored in these tables. Tables are uniquely identified by their names. Information is stored in the form of columns (also called fields) and rows (also called records). Columns contain the column name, data type, and any other attributes for the column and rows contain the records or data for the columns.

Example below shows a simple database table, containing customer’s data. The first row contains the names of the table columns.