Relational database system

Introduce

** Database management system （ Complete spelling of English ：Relational Database Management System, abbreviation RDBMS）** It is a software system designed for managing relational database , If you want to use relational database, you need to install database management system , It's actually an application .
Can be divided into ： Relational database server software 、 Relational database client software
** Relational database server software ：** Mainly responsible for managing different databases , And there will be a series of data files in each database , Data files are used to store data , In fact, a database is a collection of a series of data files .
** Relational database client software :** Mainly responsible for communicating with relational database server software , Transmit data to or obtain data from the server .

SQL

SQL(Structured Query Language) Structured query language , It's a kind of operation RDBMS The language of the database . That is to say through SQL Can operate oracle,sql server,mysql,sqlite Such relational database .

SQL The function of is to realize the communication between database client and database server ,SQL Is the bridge of communication .

Mainly can be divided into ：
DQL: Data query language , Used to query data , Such as select
DML: Data operation language , Add data 、 modify 、 Delete , Such as insert、update、delete
TPL: Transaction language , To process a transaction , Include begin transaction、commit、rollback
DCL: Data control language , Authorization and authority recovery , Such as grant、revoke
DDL: Data definition language , Do database 、 Watch management, etc , Such as create、drop

notes ：
The focus is on the growth of data 、 Delete 、 Change 、 check , Must be good at writing DQL、DML, Be able to write DDL Complete the database 、 The operation of the table , Other operations such as TPL、DCL Understanding can .
SQL Case insensitive