MySQL语法大全_自己整理的学习笔记(MySQL语句 整理二)

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

status;
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','','1988-10-2','......'); insert into student values(null,'bb','','1889-03-6','......'); insert into student values(null,'cc','','1889-08-8','......'); insert into student values(null,'dd','','1889-12-8','......'); insert into student values(null,'ee','','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='' where id=4; #删除数据 delete from student where id=5; # andselect * from student where date>'1988-1-2' and date<'1988-12-1'; # orselect * 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 '' , 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','',68,1); insert into c (id,name,sex,age,sno) values (null,'aa','',68,2); insert into c (id,name,sex,age,sno) values (null,'平平','',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='' 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;

 

posted on 2017-10-18 13:00  zhuyongzhe  阅读(136903)  评论(0编辑  收藏  举报

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