Some usage of order by

1. Handling of NULL in order by

Default handling: Oracle considers NULL to be the maximum value at order BY, so if ASC ascending is ranked at the end, desc descending is the first.

We can use Nulls first or Nulls last to control the position of NULL

Place null at the top: SELECT * FROM Student order by name ASC Nulls First

put null at the end: SELECT * FROM student ORDER BY name Desc nulls

2. Ways to sort:

Single row ascending: Select name from student order by name; (Default ascending, even if ASC is not written)
Single column descending: select name from student order by name Desc;
Multiple column ascending: Select ID, name from student order by ID, name;
Multi-column Mixed sort: Select ID, name from student ORDER by id DESC, name ASC; (By ID Descending, if the ID is the same, press name Ascending)

3. Force a column to rank first:

SELECT * FROM Student ORDER by decode (ID, 3, 1, 2), id; The value of ID 3 is ranked first

Some usage of order by