SQL Language History, Components & Elements

Posted on December 25, 2009

Definition of SQL Language:

SQL is a computer/programming language which enables a user or any application to interact with an SQL capable database management systems or DBMS. SQL is a great tool to deal with databases. It is used to access and manipulate databases & It is very easy to implement.

In this tutorial, we will explain about the basics of SQL language, its history and its implementations.

SQL stands for Structured Query Language.

It is an ANSI (American National Standards Institute) standard language used for accessing and manipulating databases.

There are different databases, such as, MySQL, SQL Server, Access, Oracle, Sybase, DB2, and other database systems. We will basically deal with Oracle.

Uses of SQL:

SQL is a very useful language. It can be used for:

• It is used to insert records in a database.
• It is used to update records in a database.
• It is used to execute queries against a database.
• It is used to retrieve data from a database.
• It is used to delete records from a database.
• It can create new database.
• It can create new tables in a database.
• It can be used to create views in a database.

History of SQL:

Before moving on its implementations, let us see the history of SQL.

IBM developed the original version of SQL at its San Jose Research Laboratory (presently known as Almaden Research Center).

1. In 1970s, IBM implemented the language, originally called Sequel, as a part of the system R project.
2. Later on, in 1974, the name of Sequel changed to SQL (Structured Query Language).
3. In 1986, the American National Standards Institute (ANSI) and the International Organization for Standardization (ISO) published in SQL standard, called SQL-86.
4. In 1987, IBM published its own corporate SQL standard, the System Application Architecture Database Interface (SAA-SQL).
5. ANSI published an extended standard for SQL, called SQL-89, in 1989.

Components / Parts of SQL Language:

• Data Definition Language (DDL): DDL is used for defining relational schemas, deleting relations, and modifying relational schemas.
• Data Manipulation Language (DML): It includes query language. It also includes commands to insert tuples , delete tuples and modify tuples in the database.
• Transaction Control: SQL includes commands for specifying the beginning and ending of transactions.

Elements of an SQL Language:

The SQL language is sub-divided into several language elements, including:

• Clauses
• Expressions
• Predicates
• Queries
• Statements

Chart to illustrate SQL Elements:

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