更新语句中的"Single-row subquery returns more than one row"

Question

我已经挣扎了几天，以弄清楚如何使我的update语句起作用。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。

代码如下：

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，tbl_metrics.act_end_time列使用表中的最低entry_timestamp值进行更新activity其中activity.caseid=tbl_metrics.caseid和activity.entry_timestamp>tbl_metrics.act_start_time，activity.act_id为 100、700 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)