sql - Oracle update based on rownum -

i need write oracle sql update column value unrelated table using rownum.

i cannot work:

update table_1 set a.id = (select b.id table_2 b          a.rownum = b.rownum) 

thanks.

just need insert value column id table. there no columns can use join rownum. possible?

use merge statement instead of update.
please find simple example below.

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test data first (id column in table_2 null):

create table table_2 select level id, chr(64+level) name dual connect level <= 5;  create table table_1 select * table_2; update table_2 set id = null; commit;  select * table_1;         id name ---------- ----          1             2 b             3 c             4 d             5 e     select * table_2;         id name ---------- ----                          b               c               d               e  

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this merge command copier id values 1 table second 1 basing on rownumns:

merge table_2 t2 using (         select *         (                 select t.*, rownum rn                 table_1 t         ) t1         join (                 select rownum rn, rowid rid                 table_2 t         ) t2         on t1.rn = t2.rn ) d on ( t2.rowid = d.rid ) when matched update set t2.id = d.id; 

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and result after merge is:

select * table_2;         id name ---------- ----          1             2 b             3 c             4 d             5 e