子查詢返回的值超過1，由於地點和組由

Question

我想做一個簡單的視圖，以便查看來自不同倉庫的庫存總量是否大於0和<是否爲所述產品的最小庫存量。

下面是代碼：

SELECT a.code, a.description, a.stk_min , b.Stk_Qty 
FROM a 
INNER JOIN b ON a.code = b.productcode 
WHERE a.stk_min > 0 and 

    (SELECT SUM(b.Stk_Qty) 
    FROM b 
    INNER JOIN a ON a.code = b.productcode 
    Group By a.code) <= a.stk_min 

當然，我得到的錯誤

子查詢返回多個值。當子查詢遵循=,!=,<,<=,>,>=或當子查詢用作表達式時，這是不允許的。

有什麼我可以做的改變呢？

Answer 1

您在尋找相關的子查詢，而不是group by。該查詢應該可以解決問題：

SELECT a.code, a.description, a.stk_min , b.Stk_Qty 
FROM a JOIN 
    b 
    ON a.code = b.productcode 
WHERE a.stk_min > 0 and 
     (SELECT SUM(b.Stk_Qty) 
     FROM b2 
     WHERE a.code = b2.productcode 
    ) <= a.stk_min; 

我懷疑你想這樣的：

SELECT a.code, a.description, a.stk_min, SUM(b.Stk_Qty) 
FROM a LEFT JOIN 
    b 
    ON a.code = b.productcode 
WHERE a.stk_min > 0 
GROUP BY a.code, a.description, a.stk_min 
HAVING COALESCE(SUM(b.Stk_Qty), 0) < a.stk_min; 

Answer 2

什麼

SELECT a.code, a.description, a.stk_min, SUM(b.Stk_Qty) SumQty 
FROM a join b on b.productcode = a.code 
group by a.code, a.description, a.stk_min 
Where a.stk_min > 0 
Having SUM(b.Stk_Qty) <= a.stk_min