SQL_lang.tex

\chapter{SQL Language}
\label{chap:SQL_lang}


SQL was first introduced for Edgar F. Codd's relational model. It has 2 parts
\begin{enumerate}
  \item data definition language (DDL)
  
  Commands: CREATE, ALTER (add/modify/remove/rename columns to existing table
  with ADD, MODIFY, DROP, RENAME), TRUNCATE (remove all data but not delete the
  table structure), RENAME (table)
  
  \item data manipulation laguage (DML)
  
  Commands: CRUD (Create, Read, Update, Delete) can be done via INSERT, MERGE,
  UPDATE, DELETE
\end{enumerate}
Newer parts
\begin{enumerate}
  \item Transaction contrl language (TCL)
  
  commands: COMMIT, ROLLBACK, SAVEPOINT
  
  \item Data control language (DCL): grant or take back control authority
  
  commands: GRANT, REVOKE
  
  \item Data query language (DQL)
  
  commands: SELECT
\end{enumerate}