使用另一个表中的值更新表中列的所有记录

Question

您好，我想用 TABLE_NAME_4MINS 表的 RequestId 更新 IIL_CHANGE_REQUEST 表的 RequestId 列的所有值，其中两个表中的 REQUESTBY 列相同。我正在尝试在 oracle daatabalse(sql developer) 中执行此操作

我的查询：

Update IIL_CHANGE_REQUEST 
set REQUESTID=(SELECT TABLE_NAME_4MINS.REQUESTID
                     FROM TABLE_NAME_4MINS
                     WHERE IIL_CHANGE_REQUEST.REQUESTBY = TABLE_NAME_4MINS.REQUESTBY) 
WHERE EXISTS (SELECT TABLE_NAME_4MINS.REQUESTID
                     FROM TABLE_NAME_4MINS
                     WHERE IIL_CHANGE_REQUEST.REQUESTBY = TABLE_NAME_4MINS.REQUESTBY)

但每次我这样做时都会收到一条错误消息：

Error starting at line : 1 in command -
Update IIL_CHANGE_REQUEST 
set REQUESTID=(SELECT TABLE_NAME_4MINS.REQUESTID
                     FROM TABLE_NAME_4MINS
                     WHERE IIL_CHANGE_REQUEST.REQUESTBY = TABLE_NAME_4MINS.REQUESTBY) 
WHERE EXISTS (SELECT TABLE_NAME_4MINS.REQUESTID
                     FROM TABLE_NAME_4MINS
                     WHERE IIL_CHANGE_REQUEST.REQUESTBY = TABLE_NAME_4MINS.REQUESTBY)

错误报告-

ORA-01427: 单行子查询返回多于一行

请任何人帮助我该怎么做。

Answer 1

您需要找到一个条件来将返回的行缩小到每个REQESTSTBY 的唯一行，例如，您可以在下面的查询中将... 替换为列名，以便根据order-by 仅返回第一行：

MERGE INTO IIL_CHANGE_REQUEST r
USING (
        SELECT *
        FROM (
           SELECT REQUESTBY, REQUESTID
                ,row_number()over(partition by REQUESTBY order by ...) rn
           FROM TABLE_NAME_4MINS
        ) 
        where rn=1
        ) t
ON (r.REQUESTBY = t.REQUESTBY)
WHEN MATCHED THEN UPDATE
   set REQUESTID=t.REQUESTID;

Answer 2

这取决于您在这种情况下要做什么。如果您不关心，请取 any 值，例如 minimum：

update iil_change_request a
set a.requestid = (select min(b.requestid)            --> here
                   from table_name_4mins b
                   where a.requestby = b.requestby) 
where exists (select c.requestid
              from table_name_4mins c
              where a.requestby = c.requestby);

如果这不是您想要的，那么您将不得不弄清楚如何处理这些“重复”。也许您必须包含另一个WHERE 条件，或者修复数据，或者......谁知道呢？我不知道，而你应该这样做。