SQL - Structured Query Language

A query is a more powerful type of filter that can gather information from multiple tables in a relational database. Some database systems provide special windows or forms for creating queries. Because of similar structure of almost all database, a common type of query language was developed. In mid 1970s, a language called structured English Query Language (SEQUEL) was developed by mainframe database developers. Later SEQUEL was changed to SQL with some improvements in it. SQL is the English like query language that allows user to query a database without much knowing about the underlying database. SQL can be used as a data definition language (DDL) and as data manipulation language (DML).