1、MySQL 语法大全select * from emp; #注释#-#-命令行连接 MySql-#启动 mysql 服务器net start mysql#关闭 net stop mysql #进入mysql -h 主机地址 -u 用户名 p 用户密码 #退出exit#-#-MySql 用户管理-#修改密码 :首先在 DOS 下进入 mysql 安装路径的 bin 目录下，然后键入以下命令 :mysqladmin -uroot -p123 password 456;#增加用户#格式:grant 权限 on 数据库.* to 用户名登录主机 identified by 密码/*如，增加一个用户 u
2、ser1密码为 password1，让其可以在本机上登录， 并对所有数据库有查询、插入、修改、删除的权限。首先用以 root 用户连入 mysql，然后键入以下命令： grant select,insert,update,delete on *.* to user1localhost Identified by “password1“; 如果希望该用户能够在任何机器上登陆 mysql，则将 localhost 改为“%“。 如果你不想 user1有密码，可以再打一个命令将密码去掉。 grant select,insert,update,delete on mydb.* to user1loca
3、lhost identified by “; */grant all privileges on wpj1105.* to sunxiaolocalhost identified by 123; #all privileges 所有权限#-#-MySql 数据库操作基础-#显示数据库show databases;#判断是否存在数据库 wpj1105,有的话先删除drop database if exists wpj1105;#创建数据库create database wpj1105;#删除数据库drop database wpj1105;#使用该数据库use wpj1105;#显示数据库中的表
4、show tables;#先判断表是否存在,存在先删除drop table if exists student;#创建表create table student(id int auto_increment primary key,name varchar(50),sex varchar(20),date varchar(50),content varchar(100)default charset=utf8;#删除表drop table student;#查看表的结构describe student; #可以简写为 desc student;#插入数据insert into student v
5、alues(null,aa,男,1988-10-2,);insert into student values(null,bb,女,1889-03-6,);insert into student values(null,cc,男,1889-08-8,);insert into student values(null,dd,女,1889-12-8,);insert into student values(null,ee,女,1889-09-6,);insert into student values(null,ff,null,1889-09-6,);#查询表中的数据select * from st
6、udent;select id,name from student;#修改某一条数据update student set sex=男 where id=4;#删除数据delete from student where id=5;# and 且select * from student where date1988-1-2 and date1988-12-1;#betweenselect * from student where date between 1988-1-2 and 1988-12-1;#in 查询制定集合内的数据select * from student where id in
7、(1,3,5);#排序 asc 升序 desc 降序select * from student order by id asc;#分组查询 #聚合函数 select max(id),name,sex from student group by sex;select min(date) from student;select avg(id) as 求平均 from student;select count(*) from student; #统计表中总数select count(sex) from student; #统计表中性别总数 若有一条数据中 sex 为空的话,就不予以统计select
8、sum(id) from student;#查询第 i 条以后到第 j 条的数据(不包括第 i 条)select * from student limit 2,5; #显示3-5 条数据#巩固练习create table c(id int primary key auto_increment,name varchar(10) not null,sex varchar(50) , #DEFAULT 男 ,age int unsigned, #不能为负值 (如为负值 则默认为0)sno int unique #不可重复);drop table c;desc c;insert into c (id,
9、name,sex,age,sno) values (null,涛哥,男,68,1);insert into c (id,name,sex,age,sno) values (null,aa,男,68,2);insert into c (id,name,sex,age,sno) values (null,平平,男,35,3);.select * from c;#修改数据 update c set age=66 where id=2;update c set name=花花,age=21,sex=女 where id=2delete from c where age=21;#常用查询语句select
10、 name,age ,id from cselect * from c where age40 and age60; #andselect * from c where age40 or age60; #orselect * from c where age between 40 and 60 #betweenselect * from c where age in (30,48,68,99); #in 查询指定集合内的数据select * from c order by age desc; #order by （asc 升序 des 降序）#分组查询select name,max(age)
11、from c group by sex; #按性别分组查年龄最大值#聚合函数select min(age) from c;select avg(age) as 平均年龄 from c;select count(*) from c; #统计表中数据总数select sum(age) from c;#修改表的名字#格式:alter table tbl_name rename to new_namealter table c rename to a;#表结构修改create table test(id int not null auto_increment primary key, #设定主键nam
12、e varchar(20) not null default NoName, #设定默认值department_id int not null,position_id int not null,unique (department_id,position_id) #设定唯一值);#修改表的名字#格式:alter table tbl_name rename to new_namealter table test rename to test_rename;#向表中增加一个字段( 列)#格式:alter table tablename add columnname type;/alter tabl
13、e tablename add(columnname type);alter table test add columnname varchar(20);#修改表中某个字段的名字alter table tablename change columnname newcolumnname type; #修改一个表的字段名alter table test change name uname varchar(50);select * from test;#表 position 增加列 testalter table position add(test char(10);#表 position 修改列
14、testalter table position modify test char(20) not null;#表 position 修改列 test 默认值alter table position alter test set default system;#表 position 去掉 test 默认值alter table position alter test drop default;#表 position 去掉列 testalter table position drop column test;#表 depart_pos 删除主键alter table depart_pos drop primary key;#表 depart_pos 增加主键alter table depart_pos add primary key PK_depart_pos(department_id,position_id);#用文本方式将数据装入数据库表中（例如 D:/mysql.txt）load data local infile “D:/mysql.txt“ into table MYTABLE;#导入.sql 文件命令（例如 D:/mysql.sql）source d:/mysql.sql; #或者 /. d:/mysql.sql;
