Question

我有2个MySQL表，其中一个有一个数字列，用于指示我需要显示的项目的顺序：

item_names

menu_id  |  dish_id  |  section_id  |  item_name
--------------------------------------------------
1        | 23        |      2       |   Pie       
1        | 24        |      2       |  Fish       
1        | 25        |      3       |  Apples     
1        | 26        |      2       |  Onions     
1        | 27        |      2       |  Chips

link_extras

extra_id |  dish_id  | sort  
-----------------------------
1        | 23        | 2     
2        | 23        | 2     
3        | 23        | 2      
1        | 24        | 0     
5        | 24        | 0     
6        | 26        | 3     
12       | 26        | 3     
1        | 27        | 1  
1        | 25        | 0

基本上我要做的是从表格menu_id中提取每个菜单section_id和item_names，并根据sort列排序输出在link_extras表中。

到目前为止：

$query="SELECT a.item_name, a.dish_id, b.sort
    FROM item_names AS a, link_extras AS b 
       WHERE a.menu_id='1'
           AND a.section_id='2'
           AND b.dish_id=a.dish_id
       GROUP BY b.dish_id
       ORDER BY b.sort";

我对数据库很陌生，所以感谢任何帮助。我追求的结果是

Fish
Chips
Pie
Onions

不幸的是，只是无法使订单正确。

Answer 1

您需要使用简单的JOIN

SELECT a.item_name, a.dish_id, b.sort
    FROM item_names AS a 
    JOIN link_extras AS b 
      ON a.dish_id = b.dish_id
   WHERE menu_id = 1
    AND section_id = 2
       GROUP BY b.dish_id
ORDER BY b.sort

输出：

| ITEM_NAME | DISH_ID | SORT |
------------------------------
|      Fish |      24 |    0 |
|     Chips |      27 |    1 |
|       Pie |      23 |    2 |
|    Onions |      26 |    3 |

See this SQLFiddle

Answer 2

SELECT
  in.item_name
FROM item_names AS in
  LEFT JOIN link_extras AS le
    ON le.dish_id = in.dish_id
WHERE in.menu_id = 1
    AND in.section_id = 2
ORDER BY le.sort

Demo Here

输出

| ITEM_NAME |
-------------
|      Fish |
|     Chips |
|       Pie |
|    Onions |

MySQL连接 - 通过另一个PHP表排序结果

2 个答案:

See this SQLFiddle