Update语句中的“单行子查询返回多个行”

Question

我已经努力了几天，以研究如何使我的update语句正常工作。 select语句似乎按预期工作，但是当我尝试更新列值时，出现ORA-01427 single-row subquery returns more than one row错误。

这是代码：

UPDATE tbl_metrics
SET act_end_time = (WITH base
AS (SELECT caseid, entry_timestamp
       FROM activity
      WHERE act_id IN (100, 700, 300)
      )  
SELECT t1.entry_timestamp
FROM base t1, tbl_metrics t2
WHERE t1.caseid = t2.caseid
AND t2.act_start_time < (SELECT MIN(t1.entry_timestamp) FROM base t1 WHERE t1.caseid = t2.caseid))

这个想法是用activity表中的最低entry_timestamp值更新tbl_metrics.act_end_time列，其中activity.caseid=tbl_metrics.caseid和activity.entry_timestamp>tbl_metrics.act_start_time且activity.act_id为activity.entry_timestamp>tbl_metrics.act_start_time或300。

Answer 1

我认为应该是这样的：

UPDATE tbl_metrics t2
SET act_end_time = 
    (SELECT MIN(t1.entry_timestamp) 
    FROM activity t1 
    WHERE act_id IN (100, 700, 300)
        AND t1.entry_timestamp > t2.act_start_time
        AND t1.caseid = t2.caseid)