表示語法錯誤而在MySQL

Question

create procedure purchaseDetailsCheckOnDelete(p_purchaseDetailsId varchar(50)) 
    begin 
     declare p_Exist tinyint(1); 
     set p_Exist = False ; 
     select p_Exist = (case count(purchaseDetailsId) when '0' then False else True end from tbl_PurchaseReturnDetails 
     where (purchaseDetailsId = p_purchaseDetailsId)); 
     select p_Exist ; 

    end 

 
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that 
corresponds to your MySQL server version for the right syntax to use near 'from 
tbl_PurchaseReturnDetails 
       where (purchaseDetailsId = p_purchaseDetailsId)' at line 5 

Answer 1

如果你有決心使用圓括號，那麼你就錯過了select，即

select p_Exist = 
     (select case count(purchaseDetailsId) 

SqlFiddle here

另外，放下支架

select p_Exist = case count(purchaseDetailsId) 
       when '0' then False else True end 
     from tbl_PurchaseReturnDetails 
     where purchaseDetailsId = p_purchaseDetailsId;   

SqlFiddle here

編輯

時間更短：

SELECT IFNULL((select 1 from tbl_PurchaseReturnDetails 
     WHERE purchaseDetailsId = p_purchaseDetailsId), 0) AS p_Exist; 

Fiddle

Answer 2

創建存儲過程嘗試這種情況：

create procedure purchaseDetailsCheckOnDelete(p_purchaseDetailsId varchar(50)) 
begin 
    declare p_Exist tinyint(1); 
    set p_Exist = False ; 
    select p_Exist = case count(purchaseDetailsId) when '0' then False else True end from tbl_PurchaseReturnDetails 
    where purchaseDetailsId = p_purchaseDetailsId; 
    select p_Exist ; 

end 

Answer 3

每個錯誤消息示出了可能的錯誤是。
在你的情況下，它說，... for the right syntax to use near 'from tbl_PurchaseReturnDetails ...。

當它說near，這意味着錯誤是之前那個特定的語句。
所以from之前的聲明是錯誤的。你把右括號放在了錯誤的地方。

更改聲明：

select p_Exist = 
    (case count(purchaseDetailsId) when '0' then False else True end 
from tbl_PurchaseReturnDetails 
    where (purchaseDetailsId = p_purchaseDetailsId)); 

到：

select p_Exist = 
    (case count(purchaseDetailsId) when '0' then False else True end) 
from tbl_PurchaseReturnDetails 
    where (purchaseDetailsId = p_purchaseDetailsId); 

Answer 4

使用此代碼段

delimiter // 
drop procedure if exists purchaseDetailsCheckOnDelete; 
create procedure purchaseDetailsCheckOnDelete(p_purchaseDetailsId varchar(50)) 
    begin 
     declare p_Exist tinyint(1); 
     set p_Exist = False ; 
     select p_Exist = (case count(purchaseDetailsId) when '0' then False else True end) as 'P_EXIST' 
     from tbl_PurchaseReturnDetails 
     where (purchaseDetailsId = p_purchaseDetailsId); 
     select p_Exist ; 
    end//