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 exitstatus;显示当前mysql的version的各种信息。 # --------------------------- # ----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user1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 user1@localhost 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 user1@localhost identified by "" ; */ grant all privileges on wpj1105.* to sunxiao@localhost 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 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 values ( 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 student; 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 date > '1988-1-2' and date < '1988-12-1' ; # or 或 select * from student where date < '1988-11-2' or date > '1988-12-1' ; # between select * 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 (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 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, 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=2 delete from c where age=21; #常用查询语句 select name ,age ,id from c select * from c where age>40 and age<60; # and select * from c where age<40 or age<60; # or select * from c where age between 40 and 60 # between select * 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) 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_name alter 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 name 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_name alter 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 table 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test alter table position add (test char (10)); #表position 修改列test alter 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test alter 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;
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MySQL语法大全
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