SQL返回至少数据

Question

我有以下结构的SQL数据：

Car_Color  | Model_tag 
---------------------- 
  Green    | Fairytail1
  Red      | Tail2
  Blue     | Fairy3
  Green    | Hi3
  Green    | Test45
  Green    | Testing34

我想得到如下输出返回以下查询：找到至少四关联的model_tag的car​​_color的所有名称，对于这些颜色，每个写入的model_tags的数量car_color。

Car_Color  | number_of_tags
----------------------------
  Green    |  4

这是我的问题：

SELECT car, model_tag
FROM Model

问题是以下查询不会返回任何数据。

Answer 1

修复聚合逻辑：

SELECT c.car_color, COUNT(mt.tag_name) as numer_of_tags 
FROM Model m JOIN
     model_tag mt
     ON mt.tag_id = m.model_id JOIN
     car c
     ON c.car_color_id = m.model_id
GROUP BY c.car_color
HAVING COUNT(mt.tag_name) >= 4;

Answer 2

如果你对model_tag.tag_name进行分组，我认为你不能得到所需的输出，试试这个：

SELECT car.car_color, COUNT (model_tag.tag_name) as numer_of_tags 
FROM Model
JOIN model_tag ON model_tag.tag_id = model.model_id
JOIN car ON car.car_color_id = model.model_id
GROUP BY car.car_color
HAVING COUNT(car.car_color_id)>=4

Answer 3

试试这个，我其实只是复制了上面的答案并放入了DISTINCT

SELECT c.car_color, COUNT(DISTINCT mt.tag_name) as numer_of_tags 
  FROM Model m JOIN
      model_tag mt
     ON mt.tag_id = m.model_id JOIN
      car c
      ON c.car_color_id = m.model_id
 GROUP BY c.car_color
HAVING COUNT(DISTINCT mt.tag_name) >= 4;