SQL Language---2

SQL Overview

First, Characteristics:

1. Integrated and unified

2. High degree of non-process: No need to specify what to do, just point out what to do

3. Set-oriented operation mode

4. Two ways to use

5. Easy and easy to learn language

Data query: Select

Data definition: Creat,drop,alter

Data manipulation: Insert,update,delete

Data Control: Grant,revork

Second, SQL supports three-level schema structure

View----out-of-mode

Basic table----Mode

Storing files in----mode

Third, the basic composition of SQL

1.data Definition Language

2. Interactive Data Manipulation language

3. Transaction control

4. Embedded SQL and dynamic SQL

5. Completeness

6. Rights Management

SQL Language---2