我有以下表结构，关系是一个 purchase_order 有多个 purchase_order_detail 和一个 purchase_order_detail 有多个 delivery_order;
采购订单
+-------------------+-------------------------+
| purchase_order_id | purchase_order |
+-------------------+-------------------------+
| 29 | Dell Computer 000001256 |
| 31 | Dell Computer 000001257 |
+-------------------+-------------------------+
purchase_order_detail
+--------------------------+-------------------+---------+------------------+
| purchase_order_detail_id | purchase_order_id | item_id | ordered_quantity |
+--------------------------+-------------------+---------+------------------+
| 26 | 29 | 279 | 100 |
| 27 | 29 | 286 | 100 |
| 28 | 29 | 287 | 100 |
| 29 | 31 | 279 | 75 |
| 30 | 31 | 286 | 85 |
+--------------------------+-------------------+---------+------------------+
delivery_order
+-------------------+--------------------------+-------------------+
| delivery_order_id | purchase_order_detail_id | recieved_quantity |
+-------------------+--------------------------+-------------------+
| 30 | 26 | 50 |
| 31 | 27 | 50 |
| 32 | 28 | 50 |
| 33 | 29 | 25 |
| 34 | 30 | 35 |
+-------------------+--------------------------+-------------------+
我想在 purchase_order_detail 表中获取 item_id 的 purchase_order 和总接收数量， 我写了这个查询，但是它返回了不正确的记录
SELECT po.created_on, po.purchase_order_id, po.purchase_order, i.item_name, SUM( do.recieved_quantity ) AS quantity
FROM purchase_order po, purchase_order_detail pod, delivery_order do , item i
WHERE i.item_id = pod.item_id
AND po.purchase_order_id = pod.purchase_order_id
AND pod.purchase_order_detail_id = do.purchase_order_detail_id
AND pod.item_id =286
+---------------------+-------------------+-------------------------+-----------+----------+
| created_on | purchase_order_id | purchase_order | item_name | quantity |
+---------------------+-------------------+-------------------------+-----------+----------+
| 2015-02-23 13:49:40 | 29 | Dell Computer 000001256 | Lenovo | 85 |
+---------------------+-------------------+-------------------------+-----------+----------+
如您所见，item_id 286 对应两个 purchase_orders。
最佳答案
您错过了 group by 子句:
SELECT po.created_on, po.purchase_order_id, po.purchase_order, i.item_name, SUM( do.recieved_quantity ) AS quantity
FROM purchase_order po, purchase_order_detail pod, delivery_order do , item i
WHERE i.item_id = pod.item_id
AND po.purchase_order_id = pod.purchase_order_id
AND pod.purchase_order_detail_id = do.purchase_order_detail_id
AND pod.item_id =286
group by po.created_on, po.purchase_order_id, po.purchase_order, i.item_name
关于php - 使用求和函数时，我的查询返回单条记录，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/28689909/