What is SQL?

Posted by admin on June 10th, 2008

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SQL stands for “Structured Query Language” and can be pronounced as “SQL” or “sequel (Structured English Query Language)” . It is a language used to communicate with a database. SQL was originally found by IBM in 1974. The commercial version of the database system was released by Oracle Corporation in 1979. SQL is an ANSI/ISO standard and is implemented my most of the relational database management systems (RDBMS) like Oracle, Microsoft SQL server, Sybase, MySQL etc. Most of these RDBMS systems have enhanced their system by adding more features to SQL, thus making it a powerful tool.

Database is a storage area used to store data in tables. The tables have a pre-defined number of columns and the data is stored in rows or records in a table. SQL is a non-procedural, English-like language used to communicate with the database and process the data in the tables.

The reason we call database as relational database management systems is because we can establish relations between different tables using constraints like primary key, foreign key etc

SQL is generally used to perform the following functions:

1) Store data
2) Modify data
3) Retrieve data
4) Delete data
5) Create table and other database objects

Few of the sql commands used in sql programming are
1) SQL statements like SELECT Statement, UPDATE Statement, INSERT INTO Statement, DELETE Statement etc
2) SQL clauses like WHERE Clause, ORDER BY Clause, GROUP BY Clause, ORDER Clause etc
3) SQL Joins, SQL Views, SQL Subquery, SQL GROUP Functions, SQL Indexes, SQL Integrity Constraints etc

Advanced SQL or Programmable SQL

The relations database systems have a advanced version of SQL known as programmable SQL. In oracle it is called PL/SQL (Procedural Language extension of SQL). Here the database objects like cursors, functions, procedures, packages, triggers etc can be created to perform various sql operations together on groups of data.

Structural information regarding database objects like tables, functions, procedures, packages can be obtained by SQL.

To learn SQL & PL/SQL you can visit these sql tutorial websites: