Q:

Find the number of days between today and specific date?

I want to find the number of days between today and selected date. 
I used one query 
SELECT DATEDIFF(CURDATE(), TILLDATE) FROM interestpr_table WHERE GLID="150";

But it returns NULL as result. How to fix?

A:

As your TILLDATE is in format YYYY-MM-DD,  you need to change it in YYYYMMDD format so that DATEDIFF would accept it as valid format. 
SQLFIDDLE 
For converting your date to format which DATEDIFF accept, you can use DATE_FORMAT like this :
SELECT DATEDIFF(curdate(),DATE_FORMAT(TILLDATE,'%Y%m%d')) // '%Y%m%d'converts it into YYYYMMDD format

SQLFIDDLE for conversion 

