MySQL各種姿勢操作

alter table teacherinfo  modify *** varchar(4) after birthday;

alter table teacherinfo change column num t_id int(10);

alter table teacherinfo drop column address;

alter table teacherinfo add column wages float;

alter table teacherinfo rename teacherinfoinfo;

create table worker (
id int(4) primary key not null,
num int(10) not null unique,
d_id int(4) ,
name varchar(20) not null,
*** varchar(4) not null,
birthday date ,
address varchar(50),
foreign key(d_id) references department(d_id)
);

show create table worker;

外來鍵約束名可以通過上一條語句檢視

alter table worker drop foreign key worker_ibfk_1;

updata table teacherinfo set birthday='1982-11-08' where num=1003;

delete from teacherinfo  where num=1002;

查詢 bumen 表中的第 4、5 條資料。limit 第乙個引數表示查詢開始的下標（從 0 開始），第二個引數表示查詢多少條資料。

select * from bumen limit 3,2;

查詢 yuangong 表中年齡在 25 - 30 之間的資料。

select * from yuangong where birthday >= 25 and birthday <= 30;

select d_id, count(d_id) from yuangong group by d_id;

根據部門查詢每個部門的最高工資

select d_id,max(salary) from yuangong group by d_id;

以左邊的資料表為準進行聯合查詢

select * from bumen left join yuangong on bumen.d_id=yuangong.d_id;

按部門分組，並計算每個部門的工資和

select d_id, sum(salary) from yuangong group by d_id;

desc 引數表示降序，去掉引數公升序排序

select * from yuangong order by salary desc;

drop index index_name on table_name;

alter table table_name drop index index_name;

alter table table_name frop primary key;

desc table_name;

create view info_view as select id, name, ***, address from work_info;

desc view_name;

update vire_name set ***='男' where id=4;

drop view view_name;

delimiter //
create procedure pfood_price_count( in price_info1 float,in price_info2 float, out count)
begin
select count(*), sum(price) into count,@sm from food where price between price_info1 and price_info2; 
end;//
delimiter ;
call pfood_price_count(2, 18, @cnt)
select cnt;

delimiter //
create function pfood_price_count(price_info1 float,price_info2 float)
returns int
deterministic
begin
declare cnt int(4);
declare sm float;
select count(*), sum(price) into cnt,sm from food where price between price_info1 and price_info2; 
return cnt;
end;//
delimiter ;
select pfood_price_count(2, 18)

delimiter //
create trigger 觸發器名字 after|before 型別(insert|delete|update|...)
on 表名 for each row
begin
觸發器執行的sql語句
end;//
delimiter ;

匯出 sql 型別檔案，可以通過改字尾名來改變檔案型別

mysqldump -u root -p dbname tablename > d:\backup\student.sql

mysql -u root -p dbname < d:\backup\student.sql

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