+-------------+----------+-----------+
| animal_name | tag_name | tag_group |
+-------------+----------+-----------+
| CatBlue | cat | species |
| CatBlue | blue | colour |
| DogBlue | dog | species |
| DogBlue | blue | colour |
| DogRed | dog | species |
| DogRed | red | colour |
+-------------+----------+-----------+
上表是各种联合表的简化视图。
它是根据所选标签返回结果的系统的一部分。问题是如果选择蓝色和猫标签，系统当前也会返回DogBlue。 （它在SQL中使用OR）
在MySQL中，如何只搜索所有标签组中包含一个或多个标签的动物？是否可以在查询中使用tag_group列值？
编辑： 我希望能够请求表格行，其中动物的颜色为蓝色，而物种 cat 。 WHERE tag_name = cat OR tag_name = blue也会带来狗。
答案 0 :(得分：1)
要获得拥有所有这些属性的SELECT animal_name
FROM table1
GROUP BY animal_name
HAVING SUM(CASE WHEN tag_name = 'cat' AND tag_group = 'species' THEN 1 ELSE 0 END ) > 0
AND SUM(CASE WHEN tag_name = 'blue' AND tag_group = 'colour' THEN 1 ELSE 0 END ) > 0
;
，您可以使用条件聚合，例如
sum(a=b)使用Mysql你也可以使用SUM(tag_name = 'blue' AND tag_group = 'colour')，sum()作为简写，使用SELECT animal_name
FROM table1
GROUP BY animal_name
HAVING SUM(CASE WHEN tag_name = 'dog' AND tag_group = 'species' THEN 1 ELSE 0 END ) > 0
AND SUM(CASE WHEN tag_name = 'blue' AND tag_group = 'colour' THEN 1 ELSE 0 END ) > 0
;
中的表达式将得到一个布尔值0/1，true / false
OR根据最后评论我需要蓝猫和蓝狗
添加SELECT animal_name
FROM table1
GROUP BY animal_name
HAVING (
SUM(CASE WHEN tag_name = 'dog' AND tag_group = 'species' THEN 1 ELSE 0 END ) > 0
AND
SUM(CASE WHEN tag_name = 'blue' AND tag_group = 'colour' THEN 1 ELSE 0 END ) > 0
) OR (
SUM(CASE WHEN tag_name = 'cat' AND tag_group = 'species' THEN 1 ELSE 0 END ) > 0
AND
SUM(CASE WHEN tag_name = 'blue' AND tag_group = 'colour' THEN 1 ELSE 0 END ) > 0
)
条件以同时拥有动物名称
{{1}}
答案 1 :(得分：0)
您可以根据条件使用子请求：
SELECT * FROM Table
INNER JOIN (
SELECT animal_name, sum(tag_name = 'blue' OR tag_name = 'cat') as sum_condition
FROM TABLE
GROUP BY animal_name
HAVING sum_condition = 2) datas USING(animal_name)
编辑回复评论
SELECT * FROM Table
INNER JOIN (
SELECT animal_name, sum(tag_name = 'blue' OR (tag_name IN ('cat','dog'))) as sum_condition
FROM TABLE
GROUP BY animal_name
HAVING sum_condition = 2) datas USING(animal_name)