Update rows in one table with data from another table based on one column in each being equal

update   table1 t1set  (    t1.column1,     t1.column2      ) = (    select      t2.column1,       t2.column2    from      table2  t2    where      t2.column1 = t1.column1     )    where exists (      select         null      from         table2 t2      where         t2.column1 = t1.column1      );

Or this (if t2.column1 <=> t1.column1 are many to one and anyone of them is good):

update   table1 t1set  (    t1.column1,     t1.column2      ) = (    select      t2.column1,       t2.column2    from      table2  t2    where      t2.column1 = t1.column1    and      rownum = 1         )    where exists (      select         null      from         table2 t2      where         t2.column1 = t1.column1      ); 

If you want to update matching rows in t1 with data from t2 then:

update t1set (c1, c2, c3) = (select c1, c2, c3 from t2 where t2.user_id = t1.user_id)where exists(select * from t2 where t2.user_id = t1.user_id)

The "where exists" part it to prevent updating the t1 columns to null where no match exists.

merge into t2 t2 using (select * from t1) t1on (t2.user_id = t1.user_id)when matched then updateset   t2.c1 = t1.c1,  t2.c2 = t1.c2