已采纳回答 / iammoon
回答如下:ALTER TABLE users2 ALTER age DROP DEFAULT KEY; 并不能删除默认约束,因为 DEFAULT 不是 key,ALTER TABLE users2 ALTER age DROP FOREIGN KEY ;也是不可以的,因为外键是表级约束。
2015-12-29
she zhi li mian jiang html5 gai cheng flash jiu ke yi yong idm xia zai shi pin le
2015-12-27
整型:TINYINT:8bit,SMALLINT:16bit,INT:32bit,MEDIUINT:24bit,BIGINT:64bit
2015-12-27
创建数据库:CREATE DATABASE [IF NOT EXITS] myfirstdb CHARACTER SET utf8,
修改:ALTER DATABASE myfirstdb CHARACTER SET utf8
删除:DROP DATABASE IF EXITS db1
查看数据库创建脚本:SHOW CREATE DATABASE db1
查看警告信息:SHOW WARNINGS;
修改:ALTER DATABASE myfirstdb CHARACTER SET utf8
删除:DROP DATABASE IF EXITS db1
查看数据库创建脚本:SHOW CREATE DATABASE db1
查看警告信息:SHOW WARNINGS;
创建数据库:CREATE DATABASE [IF NOT EXITS] myfirstdb CHARACTER SET utf8,
修改:ALTER DATABASE myfirstdb CHARACTER SET utf8
删除:DROP DATABASE IF EXITS db1
查看数据库创建脚本:SHOW CREATE DATABASE db1
查看警告信息:SHOW WARNINGS;
修改:ALTER DATABASE myfirstdb CHARACTER SET utf8
删除:DROP DATABASE IF EXITS db1
查看数据库创建脚本:SHOW CREATE DATABASE db1
查看警告信息:SHOW WARNINGS;
-D database,-h host,-u user,-p password,-P port
退出:Quit,exit,\q
退出:Quit,exit,\q
2015-12-27