Question

表格如下所示

RELATION_ID  OBJECT_ID  RELATED_TO_OBJECT_ID    CLASS_ID    RELATION_TYPE_ID
7966561       910675              69305               7             1
7966562       910675              439104              7             1

OBJECT_ID值910675在RELATED_TO_OBJECT_ID中有两个相关的OBJECT_ID值。我想找到具有最多RELATED_TO_OBJECT_ID记录的前400个OBJECT_ID以及where CLASS_ID = 7 and RELATION_TYPE_ID = 1。

Answer 1

我认为你需要沿着这些方向进行查询：

SELECT * FROM (
    SELECT OBJECT_ID, COUNT(*) as objectcount
    FROM table
    WHERE CLASS_ID = 7 AND RELATION_TYPE_ID = 1
    GROUP BY OBJECT_ID ORDER BY objectcount DESC)
 WHERE ROWNUM <= 400

内部查询创建OBJECT_ID的排序表及其出现的数量，然后外部查询获取该结果并将其限制为前400行。

注意，我没有Oracle设置，但我提到了this previous question。

Answer 2

如果您使用的是12c，则可以使用新的前n行限制功能。

SELECT OBJECT_ID,
  COUNT(*) cnt
FROM table_name
WHERE CLASS_ID       = 7
AND RELATION_TYPE_ID = 1
GROUP BY OBJECT_ID
ORDER BY cnt DESC
FETCH FIRST 400 ROWS ONLY

如果您想要包含重复项，请添加 WITH TIES 。

SELECT OBJECT_ID,
  COUNT(*) cnt
FROM table_name
WHERE CLASS_ID       = 7
AND RELATION_TYPE_ID = 1
GROUP BY OBJECT_ID
ORDER BY cnt DESC
FETCH FIRST 400 ROWS WITH TIES

找到关系最多的前400行

2 个答案: