从转换表中选择精确匹配记录

Question

大家好，我有一张包含两列trial_id，category_id

的表格

我正在附加图像以使其更清晰。

当我想要trial_id category_id的记录时，我可以运行

等查询

 SELECT * FROM `trial_category` WHERE category_id IN ( 259, 260 )

您可以将trial_id与这两个category_id

联系起来

我的问题是，现在我希望与这两个trial_id完全匹配的category_id我该怎么办？

意味着如果你只注意trial_id 73同时拥有259和260 category_id那么我的结果应该只有73。

感谢

Answer 1

SELECT trial_id, count(trial_id) AS ccnt
FROM trial_category
WHERE category_id IN ( 259,260)
GROUP BY trial_id
HAVING ccnt = 2

Answer 2

使用group by子句：

SELECT trail_id FROM `trial_category` 
WHERE category_id IN ( 259, 260 ) 
GROUP BY trial_id
HAVING count(trial_id) = 2

Answer 3

这是“set-within-sets”子查询的示例。以下是使用group by having子句的解决方案：

SELECT trial_id
FROM trial_category
group by trial_id
having sum(case when category_id = 259 then 1 else 0 end) > 0 and
       sum(case when category_id = 260 then 1 else 0 end) > 0;

当其中一行具有特定类别时，满足having子句中的每个条件。您可以看到这很容易概括为更多类别。甚至是案件259但不是260和261。

如果您希望完全这两个类别，您可以通过添加此子句来过滤没有任何其他类别的行：

       sum(case when category_id not in (259, 260) then 1 else 0 end) = 0;

IN（259,260）

Answer 4

您需要GROUP BY使用trial_id

SELECT q.* FROM (
SELECT *,COUNT(trial_id) as tcount FROM trial_category 
WHERE category_id IN ( 259, 260 ) GRUOP BY trial_id ) q
WHERE q.tcount >1

OR

SELECT *,COUNT(trial_id) as tcount FROM trial_category 
WHERE category_id IN ( 259, 260 ) GRUOP BY trial_id  HAVING tcount >1

Answer 5

试试这个

  SELECT DISTINCT trail_id FROM `trail_category` WHERE category_id IN ( 259, 260 );