我有以下表格，
mysql> select * from purchase_order;
+-------------------+-------------------------+-------+---------------------+
| purchase_order_id | purchase_order | cost | created_on |
+-------------------+-------------------------+-------+---------------------+
| 1 | Dell Computer 000001256 | 10000 | 2015-02-19 22:14:52 |
| 2 | HP Computer 000001256 | 50000 | 2015-02-19 22:14:52 |
+-------------------+-------------------------+-------+---------------------+
2 rows in set (0.00 sec)
mysql> select * from purchase_order_detail;
+--------------------------+-------------------+---------+------------------+
| purchase_order_detail_id | purchase_order_id | item_id | ordered_quantity |
+--------------------------+-------------------+---------+------------------+
| 1 | 1 | 279 | 100 |
| 2 | 1 | 286 | 100 |
| 3 | 2 | 279 | 200 |
| 4 | 2 | 286 | 300 |
+--------------------------+-------------------+---------+------------------+
4 rows in set (0.00 sec)
mysql> select * from delivery_order;
+-------------------+--------------------------+-------------------+---------------------+
| delivery_order_id | purchase_order_detail_id | recieved_quantity | recieved_on |
+-------------------+--------------------------+-------------------+---------------------+
| 1 | 1 | 50 | 2015-02-19 22:22:51 |
| 2 | 2 | 50 | 2015-02-19 22:24:59 |
| 3 | 1 | 50 | 2015-02-19 22:34:14 |
| 4 | 3 | 70 | 2015-02-20 11:11:31 |
| 5 | 4 | 150 | 2015-02-20 11:11:31 |
| 6 | 3 | 90 | 2015-02-20 11:12:20 |
| 7 | 4 | 100 | 2015-02-20 11:12:20 |
| 8 | 3 | 40 | 2015-02-20 11:12:55 |
| 9 | 4 | 50 | 2015-02-20 11:12:55 |
+-------------------+--------------------------+-------------------+---------------------+
9 rows in set (0.00 sec)
mysql> select * from stock;
+----------+-------------------+------------+----------+
| stock_id | delivery_order_id | project_id | quantity |
+----------+-------------------+------------+----------+
| 1 | 1 | 1 | 30 |
| 2 | 1 | 2 | 20 |
| 3 | 2 | 1 | 50 |
| 4 | 3 | 1 | 40 |
| 5 | 3 | 2 | 10 |
+----------+-------------------+------------+----------+
我想获取其中包含item_id = 279的购买的所有purchase_order及其库存数量。
目标是创建一个视图，我只需传递item_id，它就会获取所有purchase_order的列表，其中item_id将是输入参数及其库存总量。
所以，我已经写了这个查询，我是mysql和views
的新手select po.purchase_order_id, po.purchase_order from purchase_order po, purchase_order_detail pod where po.purchase_order_id = pod.purchase_order_id and pod.item_id = 279;
+-------------------+-------------------------+
| purchase_order_id | purchase_order |
+-------------------+-------------------------+
| 1 | Dell Computer 000001256 |
| 2 | HP Computer 000001256 |
+-------------------+-------------------------+
但它想要这样的东西，
+-------------------+-------------------------+----------+-----------+
| purchase_order_id | purchase_order | item_id | quantity |
+-------------------+-------------------------+----------+-----------+
| 1 | Dell Computer 000001256 | 279 | 100 +
| 2 | HP Computer 000001256 | 279 | 0 +
+-------------------+-------------------------+----------+-----------+
答案 0 :(得分：1)
尝试这个未经测试的查询：
select po.purchase_order_id, po.purchase_order, sum(s.quantity)
from purchase_order po
join purchase_order_detail pod on po.purchase_order_id = pod.purchase_order_id
join delivery_order do on do.purchase_order_id = pod.purchase_order_id
join stock s on s.delivery_order_id = do.delivery_order_id
where pod.item_id = 279
group by po.purchase_order_id, po.purchase_order;