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数据库操作基础-----
显示数据库
show databases;
判断是否存在数据库user,有的话先删除
drop database if exists user;
创建数据库
create database user;
删除数据库
drop database user;
使用该数据库
use user;
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;
另一写法
let sql = update student set sex=? where id=?;
let sqlVal=[sexVal,idVal]
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;
注:资料为网上摘要整理
