MySQL语法大全
时间：2021-07-01 10:21:17
帮助过：5人阅读
* 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‘,
‘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;
MySQL语法大全
标签：count 表结构 登陆 统计 mysql语法 排序 一个用户 简写 group
