How to copy one column of a table into another table's column in PostgreSQL comparing same ID

Question

I need to copy ref_id1 from table1 TO the column ref_id2 in the table2 the two things matching will be : id (same column name), a_ref1 & b_ref1 (column names are differe

Answer 1

I think this should work:

UPDATE Table2
SET ref_id2 = ref_id1
FROM Table2 
   JOIN Table1 ON 
       Table2.Id = Table1.Id AND Table2.a_ref1 = Table1.b_ref1