create procedure test()
begin
    select * from users;
end;

call test();   

create procedure test()
begin

  -- 使用 declare語(yǔ)句聲明一個(gè)變量
  declare username varchar(32) default '';
  
  -- 使用set語(yǔ)句給變量賦值
  set username='xiaoxiao';
  
  -- 將users表中id=1的名稱賦值給變量username
  select name into username from users where id=1;
  
  -- 返回變量
  select username;
end;

 create procedure test()
    begin
      declare userscount int default 0; -- 用戶表中的數(shù)量
      begin
            select count(*) into userscount from users;
            select userscount; -- 返回用戶表中的數(shù)量
      end;
      begin 
        declare maxmoney int default 0; -- 最大金額
        select max(money) into maxmoney from orders;
        select userscount,maxmoney; -- 返回用戶表中的數(shù)量、最大金額
       end;
    end;

create procedure 名稱([IN|OUT|INOUT] 參數(shù)名 參數(shù)數(shù)據(jù)類型 )
begin
......
end

 create procedure test(userId int)
    begin
        declare username varchar(32) default '';
        select name into username from users where id=userId;
        select username;
    end;

create procedure test(in userId int,out username varchar(32))
   begin
     select name into username from users where id=userId;
   end;

create procedure test6(inout userId int,inout username varchar(32))
begin
    set userId=2;
    set username='';
    select id,name into userId,username from users where id=userId;
end;

if() then...
elseif() then...
else ...
end if;

create procedure test(in userid int)
begin
   declare my_status int default 0;
   select status into my_status from users where id=userid;
   
   if(my_status=1)
   then 
       update users set score=score+10 where id=userid;
   elseif(my_status=2)
   then 
       update users set score=score+20 where id=userid;
   else 
       update users set score=score+30 where id=userid;
   end if;
end;

while(表達(dá)式) do 
   ......  
end while;

create procedure test()
begin
  declare i int default 0;
  while(i<10) do 
     begin 
        select i;
        set i=i+1;
        insert into test1(id) values(i);
     end;
  end while;
end;

repeat...until...end repeat;

create procedure test()
begin
    declare i int default 0;
    repeat 
     begin 
        select i;
        set i=i+1;
        insert into test1(id) values(i);
     end;
    until i>=10 -- 如果i>=10,則跳出循環(huán)
    end repeat;
end;

case ...
when ... then....
when.... then....
else ... 
end case;

 create procedure testcate(userid int)
    begin 
        declare my_status int default 0;
        select status into my_status from users where id=userid;
 
        case my_status
            when 1 then update users set score=10 where id=userid;
            when 2 then update users set score=20 where id=userid;
            when 3 then update users set score=30 where id=userid;
            else update users set score=40 where id=userid;
        end case;
    end;

declare 變量名 cursor ... -- 創(chuàng)建一個(gè)游標(biāo)變量
close 變量名; -- 關(guān)閉游標(biāo)

create procedure test()
    begin
        declare stopflag int default 0;
        declare username VARCHAR(32);
        declare username_cur cursor for select name from users where id%2=0;
        -- 游標(biāo)變量username_cur保存了查詢的臨時(shí)結(jié)果，即結(jié)果集
        -- 在游標(biāo)變量中數(shù)據(jù)的結(jié)尾，將變量stopflag設(shè)置為1，用于循環(huán)中判斷是否結(jié)束
        declare continue handler for not found set stopflag=1;
 
        open username_cur; -- 打卡游標(biāo)
        fetch username_cur into username; -- 游標(biāo)向前走一步，取出一條記錄放到變量username中
        while(stopflag=0) do -- 如果游標(biāo)還沒(méi)有結(jié)尾，就繼續(xù)
            begin 
                -- 在用戶名前門拼接 '_cur' 字符串
                update users set name=CONCAT(username,'_cur') where name=username;
                fetch username_cur into username;-- 游標(biāo)向前走一步，取出一條記錄放到變量username中
            end;
        end while; -- 結(jié)束循環(huán)
        close username_cur; -- 關(guān)閉游標(biāo)
    end;

-- 創(chuàng)建函數(shù)
create function 函數(shù)名(參數(shù)) returns 返回類型；
-- 函數(shù)體
begin ...... end；
-- 指定函數(shù)的返回值
returns
--函數(shù)調(diào)用
select 函數(shù)名()。

create function getusername(userid int) returns varchar(32)
    reads sql data  -- 從數(shù)據(jù)庫(kù)中讀取數(shù)據(jù)，但不修改數(shù)據(jù)
    begin
        declare username varchar(32) default '';
        select name into username from users where id=userid;
        return username;
    end;

create trigger tr_users_insert after insert on users
    for each row 
    begin 
        insert into oplog(userid,username,action,optime)
        values(NEW.userid,NEW.name,'insert',now());
    end;

create trigger tr_users_delete before delete on users
    for each row 
    begin 
        insert into oplog(userid,username,action,optime)
        values(OLD.id,OLD.name,'delete',now());
    end;

SET GLOBAL event_scheduler = 1;
-- 或者
SET GLOBAL event_scheduler = on;

--查看開(kāi)啟情況
show variables like '%event_scheduler%';

create event[IF NOT EXISTS]event_name -- 創(chuàng)建使用create event
    ON SCHEDULE schedule -- on schedule 什么時(shí)候來(lái)執(zhí)行
    [ON COMPLETION [NOT] PRESERVE] -- 調(diào)度計(jì)劃執(zhí)行完成后是否還保留
    [ENABLE | DISABLE] -- 是否開(kāi)啟事件，默認(rèn)開(kāi)啟
    [COMMENT 'comment'] -- 事件的注釋
    DO sql_statement; -- 這個(gè)調(diào)度計(jì)劃要做什么？

-- 存儲(chǔ)過(guò)程
create procedure test()
        begin 
            insert into lottery(num1,num2,num3,ctime)
            select FLOOR(rand()*9)+1,FLOOR(rand()*9)+1,FLOOR(rand()*9)+1,now();
        end;

-- 事件
create event if not exists test_event -- 創(chuàng)建一個(gè)事件
        on schedule every  3 minute -- on schedule 每三分鐘執(zhí)行一次
        on completion preserve 
        do call test;  --調(diào)用存儲(chǔ)過(guò)程