根据MySql中的多行选择一个值

Question

如果我有以下示例表：

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

如何可以选择的docId其中TAGID既是2和3，即的docId = 13。

Answer 1

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

Answer 2

假设(docId, tagId)组合是唯一的：

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

使用自我加入 。

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)