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常见的SQL语句类型： 1）DDL 数据定义语言 2）TPL 事务处理语言 3）DCL 数据控制语言 4）DML 数据操作语言查看全部
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结构化查询语言查看全部
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个放电饭锅辅导梵蒂冈梵蒂冈发光飞碟 发多少辅导fsd查看全部
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举的例子不是很恰当查看全部
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join语句分为五种类型查看全部
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select a.userid,a.username from table1 a inner join table2 b on a.userid=b.userid;查看全部
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正确使用SQL查看全部
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DML查看全部
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做外链接查看全部
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内连接查看全部
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Create Table CREATE TABLE `user_kills` ( `id` smallint(5) unsigned NOT NULL AUTO_INCREMENT, `user_id` smallint(5) unsigned DEFAULT NULL, `timestr` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, `kills` smallint(5) unsigned DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8 INSERT INTO user_kills (user_id, timestr, kills) VALUES ('2','2013-01-10 00:00:00', '10'); INSERT INTO user_kills (user_id, timestr, kills) VALUES ('2','2013-02-01 00:00:00', '2'); INSERT INTO user_kills (user_id, timestr, kills) VALUES ('2','2013-02-05 00:00:00', '12'); INSERT INTO user_kills (user_id, timestr, kills) VALUES ('4','2013-01-10 00:00:00', '3'); INSERT INTO user_kills (user_id, timestr, kills) VALUES ('2','2013-02-11 00:00:00', '5'); INSERT INTO user_kills (user_id, timestr, kills) VALUES ('2','2013-02-06 00:00:00', '1'); INSERT INTO user_kills (user_id, timestr, kills) VALUES ('3','2013-01-11 00:00:00', '20');查看全部
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-- 注意自己是否需要建库 -- create database if not exists mysqldv1; -- 新建 user1 表 create table if not exists user1 ( id smallint unsigned primary key auto_increment, user_name varchar(40), over varchar(40) )CHARSET = utf8; -- 新建 user2 表 create table if not exists user2 ( id smallint unsigned primary key auto_increment, user_name varchar(40), over varchar(40) )CHARSET = utf8; -- 新建 user_kills 表 create table if not exists user_kills ( id smallint unsigned primary key auto_increment, user_id smallint unsigned, timestr timestamp default CURRENT_TIMESTAMP, kills smallint unsigned )CHARSET = utf8;查看全部
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DROP TABLE IF EXISTS `friends`;/*悟空朋友表*/ CREATE TABLE `friends` ( `id` int(3) NOT NULL,/*sql server中不能指定int长度*/ `user_name` varchar(30) default NULL, `type` varchar(30) default NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8; INSERT INTO `friends` VALUES ('1', '孙悟空', 'friends'); INSERT INTO `friends` VALUES ('2', '牛魔王', 'friends'); INSERT INTO `friends` VALUES ('3', '蛟魔王', 'friends'); INSERT INTO `friends` VALUES ('4', '鹏魔王', 'friends'); INSERT INTO `friends` VALUES ('5', '狮驼王', 'friends'); DROP TABLE IF EXISTS `qujing`;/*取经表*/ CREATE TABLE `qujing` ( `id` int(3) NOT NULL, `user_name` varchar(30) default NULL, `type` varchar(30) default NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8; INSERT INTO `qujing` VALUES ('1', '唐僧', 'qujing'); INSERT INTO `qujing` VALUES ('2', '猪八戒', 'qujing'); INSERT INTO `qujing` VALUES ('3', '孙悟空', 'qujing'); INSERT INTO `qujing` VALUES ('4', '沙僧', 'qujing');查看全部
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中文名称：结构化查询语言查看全部
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Full join查看全部
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