Question

我收到错误＆＃34; MySQL说：＃1064 - 你的SQL语法有错误;检查与您的MySQL服务器版本对应的手册，以便在＃DEC; DECLARE @itm_qty decimal（10,2）附近使用正确的语法; DECLARE @insert_qty十进制（10,2）; SELECT @ ins＆＃39;在第1行＆＃34;。请帮助我

CREATE TRIGGER `updatestockqty` AFTER INSERT ON `billingitemtb` 
FOR EACH ROW 
AS
DECLARE @itm_qty as decimal(10,2); 
DECLARE @insert_qty as decimal(10,2);

SELECT @insert_id=i.bt_itmid from INSERTED i;

select @itm_qty=itemtb.itm_qtyinstock 
from itemtb 
where itemtb.itm_id=@insert_id;

BEGIN 
IF(i.bt_itmqty<@itm_qty)THEN 
UPDATE [db].itemtb
SET itemtb.itm_qtyinstock = itemtb.itm_qtyinstock - NEW.bt_itmqty 
WHERE itemtb.itm_id = NEW.bt_itmid; 
end IF;
END

Answer 1

至于Starter，DECALRE应该在BEGIN和END

CREATE TRIGGER `updatestockqty` AFTER INSERT ON `billingitemtb` 
FOR EACH ROW 
AS
BEGIN 
DECLARE @itm_qty decimal(10,2); 
DECLARE @insert_qty decimal(10,2);
SET @itm_qty  = select itemtb.itm_qtyinstock 
from itemtb 
where itemtb.itm_id=NEW.bt_itmid -- Change this itemID column to corresponding column in billingitem;
IF(i.bt_itmqty<@itm_qty)THEN 
UPDATE itemtb
SET itemtb.itm_qtyinstock = itemtb.itm_qtyinstock - NEW.bt_itmqty 
WHERE itemtb.itm_id = NEW.bt_itmid; 
end IF;
END

来自文档https://dev.mysql.com/doc/refman/5.7/en/declare.html

仅允许在BEGIN ... END复合语句中使用DECLARE 并且必须在任何其他陈述之前开始。

Answer 2

我得到了答案

BEGIN 
DECLARE itm_qty decimal; 
DECLARE insert_qty decimal;
declare msg varchar(128);
 select itemtb.itm_qtyinstock INTO itm_qty
  from itemtb 
  where itemtb.itm_id=NEW.bt_itmid;
if new.bt_itmqty < itm_qty THEN 
 UPDATE itemtb
 SET itemtb.itm_qtyinstock = itemtb.itm_qtyinstock - NEW.bt_itmqty 
 WHERE itemtb.itm_id = NEW.bt_itmid; 
ELSE
 set msg = concat('MyTriggerError: Trying to insert a greater qty value in 
           updatestockqty: ');
         signal sqlstate '45000' set message_text = msg;
end IF;
END

MySql触发器，声明变量不起作用

2 个答案: