Question

您好，我坚持使用mysql子查询，这是我的表

$('ul.tabs li').click(function() {
        var tab_id = $(this).attr('data-tab');

        $('ul.tabs li').removeClass('current');
        $('.tab-content').removeClass('current');

        $(this).addClass('current');
            $("#"+tab_id).addClass('current');
        });

我在子查询中尝试使用where子句在表ket_detail上显示qty，但是当我尝试它时，子查询返回多行。这是我的查询

table detail_order
==============================
id_detail | id_order | id_toko
1         | 1        | 1
2         | 1        | 2
3         | 1        | 3
4         | 1        | 4

table ket_detail
==================================
id_ket | id_detail | id_size | qty
1      | 1         | 7       | 3
2      | 1         | 9       | 1
3      | 1         | 5       | 2
4      | 2         | 7       | 8

table size
=================================
id_size | size | id_color | stock
7       | 40   | 6        | 30
9       | 42   | 6        | 20
5       | 39   | 5        | 30

table color
==========================
id_color | color
6        | green
5        | red

但是当我将大小更改为39这样的数据时

SELECT dt.id_detail, 
       SUM(tk.qty) AS tot_order, 
       COUNT(dm.color) AS tot_color,
      (SELECT ket.qty FROM ket_detail AS ket, t_size AS u 
       WHERE u.id_size=ket.id_size AND u.size = 40) AS size_40
FROM detail_order AS dt 
LEFT JOIN ket_detail AS tk ON tk.id_detail=dt.id_detail
LEFT JOIN t_size AS u ON u.id_size = tk.id_size
LEFT JOIN t_color AS dm ON dm.id_color=u.id_color
WHERE dt.id_order = 1
GROUP BY dt.id_detail

我想要的是像这样的数据

id_detail | tot_order | tot_color | size_40
============================================
1         | 6         | 2         | 2
2         | 8         | 1         | 2
3         | NULL      | 0         | 2
4         | NULL      | 0         | 2

Answer 1

您不需要子查询来获取size = 39或size = 40数据。您可以改为使用条件聚合：

SELECT dt.id_detail, 
       SUM(tk.qty) AS tot_order, 
       COUNT(dm.color) AS tot_color,
       SUM(CASE 
              WHEN u.size = 39 THEN tk.qty
              ELSE 0
           END)  AS size_39,       
       SUM(CASE 
              WHEN u.size = 40 THEN tk.qty
              ELSE 0
           END)  AS size_40        
FROM detail_order AS dt 
LEFT JOIN ket_detail AS tk ON tk.id_detail=dt.id_detail
LEFT JOIN t_size AS u ON u.id_size = tk.id_size
LEFT JOIN t_color AS dm ON dm.id_color=u.id_color
WHERE dt.id_order = 1
GROUP BY dt.id_detail;

Demo here

使用子查询执行此操作的正确方法是：

SELECT dt.id_detail, 
       SUM(tk.qty) AS tot_order, 
       COUNT(dm.color) AS tot_color,
      (SELECT SUM(ket.qty) 
       FROM ket_detail AS ket
       JOIN t_size AS u ON u.id_size=ket.id_size
       WHERE ket.id_detail = dt.id_detail AND u.size = 40) AS size_40
FROM detail_order AS dt 
LEFT JOIN ket_detail AS tk ON tk.id_detail=dt.id_detail
LEFT JOIN t_size AS u ON u.id_size = tk.id_size
LEFT JOIN t_color AS dm ON dm.id_color=u.id_color
WHERE dt.id_order = 1
GROUP BY dt.id_detail;

Demo here

如果您需要为多个尺寸选择总数量，则必须为每个所需尺寸重复子查询。因此，我认为，第一个查询提供了更清晰，更容易扩展和更高效的解决方案。

带有where子句的子查询mysql

1 个答案: