Question

我有一张看起来像这样的表：

-------------------------
| id  | areaID | itemID |
-------------------------
| 1   | 7      | 3      |
-------------------------
| 2   | 7      | 4      |
-------------------------
| 3   | 8      | 3      |
-------------------------
| 4   | 10     | 4      |
-------------------------

表示区域7具有项目3和4，区域8仅具有项目3，区域10具有项目4但没有其他项目。

我如何查询同时包含第3项和第4项的areaID？如果是上表，则只返回areaID 7。

Answer 1

只需要GROUP BY和HAVING子句

SELECT areaID
FROM table t
WHERE itemID IN (3,4)
GROUP BY areaID
HAVING COUNT(DISTINCT itemID) = 2

Answer 2

使用sum来验证每个itemID的另一种方法应该存在

select areaID
from demo
where itemID in(3,4)
group by areaID
having sum(itemID = 3) >0 
and sum(itemID = 4) > 0 ;

或使用exists

select distinct areaid
from demo a
where exists (
      select 1
      from  demo
      where itemid = 3 and areaid = a.areaid
) and (
      select 1
      from  demo
      where itemid = 4  and areaid = a.areaid
)

Demo

Answer 3

使用分组

{{1}}

Answer 4

这应该给出结果：areaID = 7

SELECT areaID
FROM table t
WHERE itemId in (3,4)
HAVING COUNT(itemId) > 1

查询哪个表具有多个列值，另一个值具有相同值？

4 个答案: