根据MySql中的多行选择一个值

Question

If I have the following example table:

id   docId   tagId
1     12      2
2     13      2
3     13      3
4     13      4
5     14      3

How can I select the docId where the tagId is both 2 and 3, ie docId = 13.

Answer 1

select docId
    from YourTable
    where tagId in (2,3)
    group by DocId
    having count(distinct tagId) = 2

Answer 2

Assuming that (docId, tagId) combination is unique:

SELECT  docId
FROM    mytable
WHERE   tagId IN (2, 3)
GROUP BY
        docId
HAVING  COUNT(*) = 2

Answer 3

SELECT docId
FROM my_table
WHERE tagId >= 2
AND tagId <= 3;

Answer 4

use Self Join .

SELECT DISTINCT t1.docId 
    FROM test AS t1 
    INNER JOIN test AS t2
    ON (t1.docId = t2.docId and t1.tagId =2 AND t2.tagId =3)