我有两张桌子:一张,主桌子显示星期几和当天的汤。餐桌汤有一个可能的汤的列表。
+-----+------------+--------+
| id | day |id_soup |
+-----+------------+--------+
| 1 | Friday | 1 |
| 2 | Saturday | 1 |
| 3 | Sunday | 2 |
+-----+------------+--------+
+-----+------------+
| id | soup |
+-----+------------+
| 1 | potatoes |
| 2 | carrots |
| 3 | peas |
+-----+------------+
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要获取星期五汤(字符串而不是 ID),我可以使用如下查询:
SELECT ma.id, ma.day, ma.id_soup, so.soup
FROM main ma, soup so
WHERE ma.id_soup = so.id
AND ma.id = 1
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我得到这样的东西(输出)
+-----+------------+---------+----------+
| id | day | id_soup | soup |
+-----+------------+---------+----------+
| 1 | Friday | 1 | potatoes |
+-----+------------+---------+----------+
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如果周五只提供一种汤,这很有效。
问题是周五将提供两种汤(土豆和豌豆 - 一系列汤)
我们需要另一张桌子吗?
编辑
+-----+---------+---------+
| id | id_day | id_soup |
+-----+---------+---------+
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 2 | 2 |
| 4 | 2 | 3 |
| 5 | 3 | 1 |
| 6 | 3 | 3 |
+-----+---------+---------+
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是否可以在单个查询中获取除了主表的其他字段(id、day、id_soup)之外,还获取 soups 数组(土豆、豌豆)?
构造此查询的最佳方法是什么?
编辑:
期望的输出(仅用于说明):
+-----+------------+---------+------------------+
| id | day | id_soup | soup |
+-----+------------+---------+------------------+
| 1 | Friday | 1 | potatoes, peas |
+-----+------------+---------+------------------+
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编辑
问题:如果期望的输出是这样的:
+-----+------------+-------------------+
| id | day | soup |
+-----+------------+---------+---------+
| 1 | Friday | potatoes, carrots |
+-----+------------+---------+---------+
| 2 | Saturday | carrots, peas |
+-----+------------+---------+---------+
| 3 | Sunday | potatoes, peas |
+-----+------------+---------+---------+
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是的,如果每天有多种汤,您将需要一张中间桌。GROUP_CONCAT您可以在声明中使用一天的所有汤SELECT。
http://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html#function_group-concat
SELECT ma.id, ma.day, GROUP_CONCAT(DISTINCT so.soup) as soup
FROM main ma
LEFT JOIN soupmain sm ON(ma.id = sm.id_main)
LEFT JOIN soup so ON(so.id = sm.id_soup)
WHERE ma.id = 1
GROUP BY ma.id
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