Question

如何选择所有商店中所有商品的数量，包括儿童商店。

Product_ID  Brand   Shop_ID
1           Bosco   10
2           Kenzo   11
3           SARA    11
4           iStyle  13
5           Patric  13
6           Kenzo   13
7           SARA    13
8           iStyle  14
9           Patric  15

Shop_ID Shop    Parent_Shop_ID
10      Shop1   
11      Shop2   10
12      Shop3   10
13      Shop4   11
14      Shop5   11
15      Shop6   14

结果必须是：

Shop_ID    Shop     Quantity_Brands
10         Shop1    9
11         Shop2    8
12         Shop3    0
13         Shop4    4
14         Shop5    2
15         Shop6    1

什么是正确的选择？

Answer 1

根据给定的数据和所有商店中的产品请求解决您问题的唯一方法

public class Peek {
    ObservableMap<Object, Image> peeks = FXCollections.observableHashMap();

    public void set(Object key, Image preview) {
        peeks.put(key, preview);
    }

    public Image get(Object key) {
        Image preview = peeks.get(key);
        return preview;
    }

}

但我想你的问题更难解决？！

Answer 2

我已经更改了数据库结构和其他东西两个检查它适合你这种方法你可以快速获取信息。

假设QTC =某些产品可用的数量我还有另一个建议，您也可以在单独的表中存储数量，这样您就不必更新主表中的详细信息，因为经常更新主表不是一个好习惯表产品

+--------+-------------+------+-----+---------+----------------+
| Field  | Type        | Null | Key | Default | Extra          |
+--------+-------------+------+-----+---------+----------------+
| p_id   | int(50)     | NO   | PRI | NULL    | auto_increment |
| brand  | varchar(50) | NO   |     | NULL    |                |
| shp_id | int(50)     | NO   |     | NULL    |                |
| qtc    | int(25)     | NO   |     | NULL    |                |
+--------+-------------+------+-----+---------+----------------+

餐馆

+--------+-------------+------+-----+---------+----------------+
| Field  | Type        | Null | Key | Default | Extra          |
+--------+-------------+------+-----+---------+----------------+
| shp_id | int(11)     | NO   | PRI | NULL    | auto_increment |
| name   | varchar(11) | NO   |     | NULL    |                |
+--------+-------------+------+-----+---------+----------------+



SELECT shop.name, SUM(product.qtc) FROM shop INNER JOIN product ON shop.shp_id = product.shp_id GROUP BY shop.shp_id

选择所有产品的数量

2 个答案: