Mysql常用命令行大全（四）外键及其它

表构成

mysql> show tables;

+----------------------+
| Tables_in_WebComplie |
+----------------------+
| Compile |

| Content |
| User      |
+----------------------+

Compile表结构

mysql> show create table Compile;

| Compile | CREATE TABLE `Compile` (
`compileID` int(11) NOT NULL AUTO_INCREMENT,
`userName` varchar(128) NOT NULL,
`boardName` varchar(128) NOT NULL,
`panelName` varchar(128) NOT NULL,
`contentID` int(11) NOT NULL,
`complieDate` datetime NOT NULL,
`binPath` varchar(128) NOT NULL,
`compileState` tinyint(1) NOT NULL,
PRIMARY KEY (`compileID`),
UNIQUE KEY `UQ_Compile_CompileID` (`compileID`),
KEY `ContentID` (`contentID`),
KEY `Compile_Panel_PanelName` (`panelName`),
KEY `Compile_User_UserName` (`userName`),
CONSTRAINT `Compile_User_UserName` FOREIGN KEY (`userName`) REFERENCES `User` (`userName`),
CONSTRAINT `Compile_ibfk_2` FOREIGN KEY (`contentID`) REFERENCES `Content` (`contentID`),
CONSTRAINT `Compile_Panel_PanelName` FOREIGN KEY (`panelName`) REFERENCES `Panel` (`PanelName`)
) ENGINE=InnoDB AUTO_INCREMENT=30 DEFAULT CHARSET=latin1 |

删除外键“UserID”：

mysql> alter table Compile drop foreign key Compile_User_UserName;  //注意删除的是外键约束“Compile_User_UserName”，即外键UserID

增加外键：

mysql> alter table Compile add constraint Compile_User_UserName foreign key(userName) references User(userName);