MySQL MAX function always returns 99

Hi,

Yesterday I encounter a silly problem: I wanna get the max value of UserID, and try the MAX function, like this

SELECT MAX(userid) AS max FROM usertable;

Code (markup):

But the MAX function always returns 99, not the highest value (about 200+).
Tried google, and I found nothing

After that, I think there's some error with the data type, as the MAX is used for number only.

Then, I changed the data type from VARCHAR to INT, and all works

So, I made a post and hope this will help someone

 

Is there a problem with using an INT field vs. a VARCHAR? The max or any other comparison function will not work properly on a non numerical field.

 

Great never tried this indeed

thanks