What is cause of ORA-38104 error on SQL merge?

Question

I have a code like this

MERGE INTO target_table tgt
USING source_table src
on(tgt.c1=src.c1)
WHEN MATCHED THEN
UPDATE SET tgt.c1=src.c2

I g

Answer 1

You can exploit some workarounds for ORA-38104, which seem to work up until Oracle 18c, including this one, where you'd wrap your columns in a row value expression that contains an additional dummy expression:

MERGE INTO target_table tgt
USING source_table src
ON ((tgt.c1, 'dummy') = ((src.c1, 'dummy')))
WHEN MATCHED THEN
UPDATE SET tgt.c1=src.c2