Update column values with result from group values (MIN) of linked table

I have two tables Table 1 (main) and Table 2,connected with T1.

I need to delete double entries in Table 1. TO do that before any delete in T1 I must delete or update the data in T2.

The option chosen is to update T2 data to point with entries not to be deleted in T1.

SQL Problem :

I have the following group by expresion :

SELECT min(t1.id) minid
                ,max(t1.id) maxid
                ,t1.t1_value t1valor
                ,t1.group_id grupo
                ,t1.date_begin
                ,t1.date_end
                ,count(*)
            FROM rs2qtt1 t1
            WHERE t1.t1_value LIKE '%B0%'
            GROUP BY t1.t1_value
                ,t1.group_id
                ,t1.date_begin
                ,t1.date_end
            HAVING count(*) > 1
            ORDER BY count(*) DESC
                ,t1.t1_value
                ,t1.group_id
                ,t1.date_begin

I want to do something like that avoiding PL/SQL if it’s possible.

UPDATE rs2qtt2 t2
SET t2.rg_id = minid
WHERE t2.rg_id IN ( 
        SELECT maxid max2
        FROM (
            SELECT min(t1.id) minid
                ,max(t1.id) maxid
                ,t1.t1_value t1valor
                ,t1.group_id grupo
                ,t1.date_begin
                ,t1.date_end
                ,count(*)
            FROM rs2qtt1 t1
            WHERE t1.t1_value LIKE '%B0%'
            GROUP BY t1.t1_value
                ,t1.group_id
                ,t1.date_begin
                ,t1.date_end
            HAVING count(*) > 1
            ORDER BY count(*) DESC
                ,t1.t1_value
                ,t1.group_id
                ,t1.date_begin  
            )
        );  

But obviously the minid in the set statement is not visible.

Answer

You can prepare the required values in a query with saved rowid from rs2qtt2 and then use it as source data for merge query like

merge into rs2qtt2 dst using (
    select t2.rowid row_id, t1.minid new_id
    from (
        SELECT min(t1.id) minid, max(t1.id) maxid
        FROM rs2qtt1 t1
        WHERE t1.t1_value LIKE '%B0%'
        GROUP BY t1.t1_value, t1.group_id, t1.date_begin, t1.date_end
        HAVING count(*) > 1
    ) t1 inner join rs2qtt2 t2 on (t2.rg_id = t1.maxid)
) src
on (dst.rowid = src.row_id)
when matched then update set dst.rg_id = src.new_id;

This should help to avoid ORA-38104 and should access rows for merging directly by rowid