How to select top N from a table

Question

I have to select the top 25 records from a table according to the column Num.

There are two issues. First, the table is not sorted by Num.

Answer 1

Oracle:

Select *
FROM Table
WHERE rownum <= 25

MSSQL:

SELECT TOP 25 * 
from Table

Mysql:

SELECT * FROM table
LIMIT 25