MySQL 的工作中的常用语法

#------------code---------------
/* code */

net start mysql

net stop mysql  

mysql -h 主机地址 -u 用户名 －p 用户密码 

exit

mysqladmin -uroot -p123 password 456;

/*
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*/

show databases;

drop database if exists wpj1105;

create database wpj1105;

drop database wpj1105;

use wpj1105;

show tables;

drop table if exists student;

create table student(
id int auto_increment primary key,
name varchar(50),
sex varchar(20),
date varchar(50),
content varchar(100)
)default charset=utf8;

drop table student;

describe student;  #可以简写为desc student;

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;

update student set sex='男' where id=4;

delete from student where id=5;

select * from student where date>'1988-1-2' and date<'1988-12-1';

select * from student where date<'1988-11-2' or date>'1988-12-1';

select * from student where date between '1988-1-2' and '1988-12-1';

select * from student where id in (1,3,5);

select * from student order by id asc;

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;

select * from student limit 2,5;  /*显示3-5条数据*/

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;

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;

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）*/

select name,max(age) from c group by sex;  /*按性别分组查年龄最大值*/

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;

/*格式:alter table tbl_name rename to new_name*/
alter table c rename to a;

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*/
);

/*格式:alter table tbl_name rename to new_name*/
alter table test rename to test_rename;

/*格式:alter table tablename add columnname type;/alter table tablename add(columnname type);*/
alter table test add  columnname varchar(20);

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;

alter table position add(test char(10));

alter table position modify test char(20) not null;

alter table position alter test set default 'system';

alter table position alter test drop default;

alter table position drop column test;

alter table depart_pos drop primary key;

alter table depart_pos add primary key PK_depart_pos
(department_id,position_id);

load data local infile "D:/mysql.txt" into table MYTABLE;

source d:/mysql.sql;  #或者  /. d:/mysql.sql;