Mysql Tutorial

1. Oracle初步了解

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Jun 07, 2016 pm 03:38 PM

oraclepsqllearndevelopment tools

Oracle 开发工具 1. SQL Plus 使用Oracle之前，需先打开Oracle服务，如图所示：在开始菜单中找到SQL Plus并打开，如图所示：打开SQL Plus，输入用户名和密码（scott/tiger），如图所示： 2. PLSQL Developer 点击左上角的new–Command Window，出现编辑sql

Oracle

开发工具

1. SQL Plus
使用Oracle之前，需先打开Oracle服务，如图所示：
1. Oracle初步了解
在开始菜单中找到SQL Plus并打开，如图所示：

打开SQL Plus，输入用户名和密码（scott/tiger），如图所示：

2. PLSQL Developer

点击左上角的new–>Command Window，出现编辑sql命令界面，如图所示：

数据库表准备

导入D盘下的del_data.sql数据库文件，如图所示：
再导入D盘下的hr_cre.sql数据库文件，如图所示：
最后导入D盘下的hr_popul.sql数据库文件，如图所示：
表间的关系，如图所示：

SQL语句分为以下三种类型：

<code>DML：Data Manipulation Language数据操作语言
DDL ：Data Definition Language数据定义语言
DCL ：Data Control Language数据控制语言
</code>

DML

DML用于查询与修改数据记录，包括如下SQL语句：
-INSERT：添加数据到数据库中
-UPDATE：修改数据库中的数据
-DELETE：删除数据库中的数据
-SELECT：选择（查询）数据

DDL

DDL用于定义数据库的结构，比如创建、修改或删除数据库对象，包括如下SQL语句：
-CREATE TABLE：创建数据库表
-ALTER TABLE：更改表结构、添加、删除、修改列长度
-DROP TABLE：删除表
-CREATE INDEX：在表上建立索引
-DROP INDEX：删除索引

DCL

DCL用来控制数据库的访问，包括如下SQL语句：
-GRANT：授予访问权限
-REVOKE：撤销访问权限
-COMMIT：提交事务处理
-ROLLBACK：事务处理回退
-SAVEPOINT：设置保存点
-LOCK：对数据库的特定部分进行锁定

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