MySQL存儲過程語法

先上一段代碼

/*
建立字符串split函數
*/
DROP FUNCTION
IF EXISTS SPLIT_STR;
CREATE FUNCTION SPLIT_STR(
  x VARCHAR(255),
  delim VARCHAR(12),
  pos INT
)
RETURNS VARCHAR(255)
RETURN REPLACE(SUBSTRING(SUBSTRING_INDEX(x, delim, pos),
       LENGTH(SUBSTRING_INDEX(x, delim, pos -1)) + 1),
       delim, '');

/*
建立同步店鋪頭像的存儲過程
*/
DROP PROCEDURE
IF EXISTS SCHEMA_CHANGE_1;
DELIMITER $$
CREATE PROCEDURE SCHEMA_CHANGE_1 ()
BEGIN
    declare _merchant_id bigint;
    declare _shop_icon varchar(1500);
    DECLARE done INT DEFAULT FALSE; 
    Declare maxPicId bigint;
    declare cur cursor for (
    select merchant_id,concat("https://",wenjianlj,".oss-cn-hangzhou.aliyuncs.com/",wenjianmc) as path
from (
select t2.merchant_id,SPLIT_STR(shanghutp,"_",1) as guid,SPLIT_STR(shanghutp,"_",2) as verfiCode
from (select distinct merchant_id
        from (
        select
        a.merchant_id as merchant_id,
        b.id as picId
        from mdse_shop as a
        left join mdse_pic as b on a.shop_icon=b.id) t1 where picId is null) t2
inner join yygl_v_shangjiaxx as shangjia on t2.merchant_id=shangjia.shanghubh) t3
inner join xtgy_wenjianccsy as wenjian on t3.guid=wenjian.guid and t3.verfiCode=wenjian.yanzhengma
    );
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE; -- 監聽器  
    set maxPicId = (select id from mdse_pic order by id desc limit 1);
    open cur;
    label:LOOP  
        FETCH cur INTO _merchant_id,_shop_icon;  
        select _merchant_id,_shop_icon;
        set maxPicId = (maxPicId + 1);
        insert into mdse_pic(id,path) value(maxPicId,_shop_icon);   -- 添加圖片記錄
        update mdse_shop set shop_icon= maxPicId where merchant_id=_merchant_id;  -- 門店關聯圖片記錄主鍵
        IF done THEN LEAVE label;END IF;  
    END LOOP label; 
    close cur; 
END$$
DELIMITER ;


CALL SCHEMA_CHANGE_1 ();

　　

一、刪除函數語法

drop function 函數名稱;

一般會和if exists聯合使用。drop function if exists 函數名稱;

 

二、建立函數語法

create function 函數名稱（

參數名稱 參數類型,

參數名稱 參數類型,

...

）

returns 返回值類型

return {

sql 邏輯語句

}

 

三、刪除存儲過程

drop procedure 存儲過程名稱;

一般會和if exists聯合使用，drop procedure if exists 存儲過程名稱;

 

四、指定指令結束符 開始

DELIMITER $$

 

五、從新指定指令結束符爲;

DELIMITER ;

 

六、建立存儲過程語法

create procedure 存儲過程名稱()

begin

存儲過程內容

end 指令結束符

 

七、聲明存儲過程變量

declare 變量名稱  變量類型 [default 默認值];

 

八、修改變量值

set 變量名稱=變量值;

 

九、聲明遊標

declare 遊標名稱 cursor for (select查詢);

 

十、聲明遊標監聽器

DECLARE done INT DEFAULT FALSE; 

DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE; -- 監聽器  

若是找不到下一條記錄，則把一個標誌位變動

 

十一、開啓遊標，關閉遊標

open cur;

操做遊標

close cur;

 

十二、遍歷遊標

label:LOOP 

FETCH cur INTO _merchant_id,_shop_icon;  

IF done THEN LEAVE label;END IF;  

END LOOP label;

 

1三、從遊標獲取一行記錄到變量中

FETCH cur INTO _merchant_id,_shop_icon

注意一點 遊標中的列名稱不能和變量名重複，負責不會對變量進行賦值

 

1四、調用存儲過程

CALL 存儲過程名稱 ();