comparision operater(>) between two date time picker and textbox

Question

hi friends,
  i am using using two date time pickers and one textbox with name leaveblance in my application i am calculating no.days between two dates in stored procedure and storing leaveblance, and no.days in one table which is not related to my form table it is different table now i want to use if conditon to no.days and leaves left showing message insufficient leaves that means if condition should compare between two columns of different table  in my form and i have taken one textbox leaves left which will take data from different table and it will display when i enter employee code. could any one help me.

thanks