SQL or Structured Programming Language is a very old language. It evolves from relational algebra’s offshoot called the Set Theory. Boolean Algebra deals with boolean operators. The basic operators being NOT, OR and AND. The other operators like NOR, XOR and NAND are aggregation of the basic operators.
SQL operations are of 5 types. They are:
1. DML – Data Modification Language
2. DQL – Data Query Language
3. DDL – Data Definition Language
4. DCL – Data Control Language
5. TCL – Transaction Control Language
DML revolves around commands like INSERT, UPDATE and DELETE.
DQL is a query command called SELECT
DDL comprises of commands like CREATE, ALTER
DCL is for security and has commands like GRANT and REVOKE
TCL is used for transactions and commands include COMMIT and ROLLBACK
SQL is a very ‘ENGLISH’ like language and is quite simple for anyone to learn. DML operations are a part of OLTP (Online Transaction Processing) systems and so is TCL.
DQL is a characteristic of BI (Business Intelligence) systems because you are simply trying to query. Sometimes this is also called Business Analytics.
DDL is mainly used to create and alter the design sometimes also called as SCHEMA.
DCL is used in conjunction with privilege settings.
Nowadays there is something called NOSQL which does not use SQL as its primary interface to data. Instead it works on key-value pairs as data, parsing them and generating solutions on a large distributed network array. You may have heard of Big data (velocity, volume and variety). NOSQL works on big data. It’s not an alternative to SQL, but complements it very well.