比较不同的表后，PL / SQL更新多行

Question

couldn't find anything similar on google or through searching through this site so i figured i'd ask.

What I'm trying to do is update a global temp table's (named GTT) rows in a column called Ent_Name with rows from a column named Modified_Name in table MN_Xref wherever OG_Name (also from MN_Xref) = GTT.Ent_Name. If there is no OG_Name that matches with Ent_Name then Ent_Name should not be updated. GTT has already been populated at this point. How could this be done?

I can provide more info if need be. Thanks!

Answer 1

Here for this kind of scenario MERGE will be one of the good options. Hope below snippet helps.

MERGE INTO GTT USING MN_REF
ON ( gtt.ENT_NAME = MN_REF.OG_NM)
WHEN MATCHED THEN 
UPDATE SET
ENT_NAME = MN_REF.MODIFIED_NAME;

Answer 2

This should work for you

UPDATE 
(
   select GTT.Ent_Name          old_name
        , MN_Xref.Modified_Name new_name
   FROM GTT INNER JOIN MN_Xref ON (GTT.Ent_Name = MN_Xref.OG_Name)
)
SET old_name = new_name;

Answer 3

if i got your problem correctly this should solve it

    declare 
  cursor c is
select * from MN_Xref;

begin
for i in c loop
update GTT g
   set g.Ent_Name = i.Modified_Name
 where g.Ent_Name = i.OG_Name;
commit;
end loop;
end;