Question

我正在尝试读取与同一字段中多个值匹配的记录。表格示例：A

UserID  License
1   DOG
1   CAT
1   FISH
2   DOG
2   CAT
3   FISH
4   CAT
4   DOG
4   FISH
5   CAT
5   FISH

如何提取具有三个DOG，CAT和FISH许可证的UserID？

我不确定在这里如何使用INNER JOIN，因为没有两个表。最好的方法是什么？

谢谢 PG

Answer 1

甚至不需要考虑不必要的 INNER JOIN。让我们使用IN

SELECT UserID FROM A WHERE License IN('DOG','CAT','FISH');

注意事项，但是我仍然对此行有点困惑，尽管我该如何提取具有全部三个许可证DOG，CAT和FISH的UserID？

已编辑：这消除了我对 all 的困惑，请尝试以这种方式从输出中仅获取UserId。

SELECT UserID,count(*) as lnt FROM A WHERE 
  License IN('DOG','CAT','FISH') 
group by UserId having lnt = 3;

输出：

UserID  lnt
  1     3
  4     3

小提琴： http://sqlfiddle.com/#!9/e563ef/4

Answer 2

您可以在SQL中使用case when...，如下所示：

SELECT UserID, SUM(CASE WHEN License IN ("DOG", "CAT", "FISH") THEN 1 ELSE 0 END) AS LICENSE_COUNT
FROM EXAMPLE_TABLE
GROUP BY UserID
HAVING LICENSE_COUNT = 3

Answer 3

“如何提取具有三个DOG，CAT和FISH许可证的UserID？”

赞：

SELECT USERID, COUNT(*) AS LICENSE_COUNT
  FROM EXAMPLE_TABLE
  GROUP BY USERID
  HAVING COUNT(*) = 3

dbfiddle here

Answer 4

尝试这样：

select userid 
from example_table 
WHERE License IN('DOG','CAT','FISH') group by user_id having count(distinct License)=3

Answer 5

正如其他答案所述，最好使用IN运算符而不是Join。即使不使用group by或HAVING，也可以获得所需的结果。试试这个

Select DISTINCT(UserId) from A 
Where UserID IN(Select userId from A where License='DOG') 
AND UserID IN (Select UserId from A where License='CAT') 
AND UserID IN (Select UserId from A where License='FISH')

如何读取与同一字段中多个值匹配的记录？

5 个答案: