MySQL來計算SUM與外鍵關係

Question

我有兩個表1.material_line_item和2.item_master有兩個表之間的外鍵關係（item_master_id目前在material_line_item），有一個在item_master叫item_code列。所以我想要一個連接查詢來顯示當前查詢的item_code。

Answer 1

我會通過將item_master表加入子查詢material_line_item來解決這個問題，該子查詢會計算每個項目主標識值所需的聚合。儘管您可以自由選擇所需的列，但我正在選擇所有列。

SELECT t1.*, t2.* 
FROM item_master t1 
INNER JOIN 
(
    SELECT item_master_id, 
      SUM(received_quantity) AS Total_Received_Qty, 
      SUM(ordered_quantity) AS Total_Ordered_Qty 
    FROM material_line_item 
    GROUP BY item_master_id 
) t2 
    ON t1.id = t2.item_master_id 

Answer 2

你可以簡單地連接兩個表像

select item.item_master_id, master.item_id, Sum(received_quantity), 
sum(ordered_quantity) from material_line_item item 
left join item_master master on item.item_master_id = master.id 
group by item.item_master_id, master.item_id 

Answer 3

試試這個，

select a.item_master_id,a.Total_received_qty,a.Total_ordered_Qty,b.item_code from (select  item_master_id, 
     sum(received_quantity) Total_received_qty, 
     sum(ordered_quantity) Total_ordered_Qty 
     from material_line_item 
     group by item_master_id) a, item_master b where a.item_master_id =b.item_master_id 

希望這將有助於。