How to update more than one row in pl/sql

Question

I'm trying to update a column in a table on every row from a query. The code I have is:

UPDATE CUSTOM_ISR_ASSET_DETAILS SET COUNTSYSTEMASSETS = ( Select  Count(PARENT_ID) as COUNTSYSTEMASSETS 
                              from PM_ENTITY 
                              inner join
                                (SELECT 
                                pm_entity.PM_ENTITY_ID,
                                response_text.response_text
                                FROM pm_entity 
                                INNER JOIN response_text  
                                ON pm_entity.pm_entity_id=response_text.parent_id 
                                AND response_text.question_id = '000ZLIJCA0003MI82Z000UWLUTG000000P4V') TBL_StandardRollup
                              on PM_ENTITY.PM_ENTITY_ID = TBL_StandardRollup.PM_ENTITY_ID
                              WHERE (TBL_StandardRollup.response_text = 'Standard')
                              group by PARENT_ID); 

What I'm trying to do is update each row with a count for each parent id but, obviously, this returns > 1 row so the update fails. So, I can't do this with this sql code.

How can I do this so that each row is updated with a count of parent ids?

Answer 1

Please try use merge statement. This would be something like:

merge into CUSTOM_ISR_ASSET_DETAILS c
using (/*YOUR SUB_QUERY*/) d
on (d.response_text = c./*what column 'standard' come from*/)
when matched then update set COUNTSYSTEMASSETS = d.COUNTSYSTEMASSETS;

I'm not able to define what is join condition. I guess on column where value 'standard' comes from.

Answer 2

You have SELECT COUNT(x) GROUP BY x I think what you need is to correlate that query and have it only return one row:

UPDATE CUSTOM_ISR_ASSET_DETAILS
SET COUNTSYSTEMASSETS = (
    SELECT  Count(PARENT_ID)
    FROM whatever
    WHERE whatever.PARENT_ID = CUSTOM_ISR_ASSET_DETAILS.PARENT_ID ) ;

That way the subquery is returning only a single row corresponding to the row you are updating.