select * from emp;  #註釋
#---------------------------
#----命令行連接MySql---------
 
#啟動mysql服務器
net start mysql
 
#關閉 
net stop mysql
  
#進入
mysql -h 主機地址 -u 用戶名 －p 用戶密碼
 
#退出
exit

status;
顯示當前mysql的version的各種信息。
 
#---------------------------
#----MySql用戶管理---------
 
#修改密碼:首先在DOS 下進入mysql安裝路徑的bin目錄下，然後鍵入以下命令:
mysqladmin 
 
-uroot -p123 password 456;
 
#增加用戶
#格式:grant 權限 on 數據庫.* to 用戶名@登錄主機 identified by ‘密碼‘
/*
如，增加一個用戶user1密碼為password1，讓其可以在本機上登錄， 並對所有數據庫有查詢、插入、修改、刪除的權限。首先用以root用戶連入mysql，然後鍵入以下命令：
grant select,insert,update,delete on *.* to user1@localhost Identified by "password1";
如果希望該用戶能夠在任何機器上登陸mysql，則將localhost改為"%"。
如果你不想user1有密碼，可以再打一個命令將密碼去掉。
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 所有權限
 
#----------------------------
#-----MySql數據庫操作基礎-----
 
#顯示數據庫
show databases;
 
#判斷是否存在數據庫wpj1105,有的話先刪除
drop database if exists wpj1105;
 
#創建數據庫
create database wpj1105;
 
#刪除數據庫
drop database wpj1105;
 
#使用該數據庫
 
use wpj1105;
 
#顯示數據庫中的表
show tables;
 
#先判斷表是否存在,存在先刪除
drop table if exists student;
 
#創建表
create table student(
id int auto_increment primary key,
name varchar(50),
sex varchar(20),
date varchar(50),
content varchar(100)
)default charset=utf8;
 
#刪除表
drop table student;
 
#查看表的結構
describe student;  #可以簡寫為desc student;
 
#插入數據
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‘,‘......‘);
#查詢表中的數據
select * from student;
select id,name from student;
 
#修改某一條數據
update student set sex=‘男‘ where id=4;
 
#刪除數據
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 查詢制定集合內的數據
select * from student where id in (1,3,5);
 
#排序 asc 升序  desc 降序
select * from student order by id asc;
 
#分組查詢 #聚合函數
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;   #統計表中總數
 
select count(sex) from student;   #統計表中性別總數  若有一條數據中sex為空的話,就不予以統計~
 
select sum(id) from student;
 
#查詢第i條以後到第j條的數據(不包括第i條)
select * from student limit 2,5;  #顯示3-5條數據
 
#鞏固練習
create table c(
 id int primary key auto_increment,
 name varchar(10) not null,
 sex varchar(50) ,  #DEFAULT ‘男‘ ,
 age int unsigned, #不能為負值(如為負值 則默認為0)
 sno int unique    #不可重復
);
 
drop table c;
desc c;
 
insert into c (id,name,sex,age,sno) values (null,‘濤哥‘,‘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;
 
#修改數據
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;
 
#常用查詢語句
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 查詢指定集合內的數據
select * from c order by age desc;      #order by （asc升序 des降序）
 
#分組查詢
select name,max(age) from c group by sex;  #按性別分組查年齡最大值
#聚合函數
select min(age) from c;
select avg(age) as ‘平均年齡 ‘ from c;
select count(*) from c;  #統計表中數據總數
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;
  
#表結構修改
create table test
(
id int not null auto_increment primary key, #設定主鍵
name varchar(20) not null default ‘NoName‘, #設定默認值
department_id int not null,
position_id int not null,
unique (department_id,position_id) #設定唯一值
);
 
#修改表的名字
#格式:alter table tbl_name rename to new_name
alter table test rename to test_rename;
 
#向表中增加一個字段(列)
#格式:alter table tablename add columnname type;/alter table tablename add(columnname type);
alter table test add  columnname varchar(20);
 
#修改表中某個字段的名字
alter table tablename change columnname newcolumnname type;  #修改一個表的字段名
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 默認值
alter table position alter test set default ‘system‘;
#表position 去掉test 默認值
alter table position alter test drop default;
#表position 去掉列test
alter table position drop column test;
#表depart_pos 刪除主鍵
alter table depart_pos drop primary key;
#表depart_pos 增加主鍵
alter table depart_pos add primary key PK_depart_pos
(department_id,position_id);
 
#用文本方式將數據裝入數據庫表中（例如D:/mysql.txt）
load data local infile "D:/mysql.txt" into table MYTABLE;
 
#導入.sql文件命令（例如D:/mysql.sql）
source d:/mysql.sql;  #或者  /. d:/mysql.sql;

MySQL語法大全