How to match the interval and count

[#1]

Hi

I have calendar date.

AP        Year   Start date        end date

AP01     2012   2-Jan-12  1-Feb-12

AP02     2012    2-Feb-12  28-Feb-12

.

.

Now i have an column induction date plan is  as 5-Jan-12

now all the records in induction date has to check the calendar start and end date and it show count as 1 for AP01.

which columns should i link.. should i use interval match.. if so how ?? or in expression is it simple ??