Easy way to select numerical data from MySQL table

I'll explain this using a example,


Lets thing we have table called EMP and column called SALARY.
Now suppose there are numerical data and string data in the SALARY column. (ex: 12000, 25000, not available, null...)
For this kind of columns we can use following method to select only numerical data;


SELECT SALARY FROM EMP WHERE (SALARY+0)!=0;