NULL Value and Order By

By default, when we order the records by columns, the null values are ranked last.

SQL> select * from TBL_TEST3 order by a, b;

        ID          A          B
---------- ---------- ----------
         1          1          2
         2          1
         4          2          2
         3

We can place rows with nulls first by specifying "nulls fist".

SQL> select * from TBL_TEST3 order by a nulls first, b;

        ID          A          B
---------- ---------- ----------
         3
         1          1          2
         2          1
         4          2          2