IF in query

[Ronny Drechsler-Hildebrandt]

Hi

I am afraid I need your help to create a part of a query.
Situation. We have a small booking applikation which stores the booked data in two fields "from" and "till".
Example: A person books a room "from" 2014-11-27 "till" 2014-12-03.
Now I wolud like to read out "the workload" of the rooms per month.
The month will be provided as an varibale (PHP) $month_i_wanted_to_know

Therefore I need to make three differences in my query

1. Case:

"from" and "till" conatins the same month
So in MySql the question will something like:

"IF(MONTH(from) == MONTH(TILL) == $month_i_wanted_to_know)"

QUERY -> SELECT SUM(DATEDIFF(from,till)) AS AMOUNT


2. Case:
"from" contains the month for which I want to have the data and "till" is in the next or other month.
So the question will be something like that:

"IF(MONTH(from) == $month_i_wanted_to_know AND MONTH(till) > $month_i_wanted_to_know"

QUERY -> SELECT SELECT SUM(DATEDIFF(from,LAST_DAY(from))) AS AMOUNT

3. Case:
"till" contains the month for which I want to have the data and "from" is the month before.

So the question will be something like that:

"IF(MONTH(till) == $month_i_wanted_to_know AND MONTH(from) < $month_i_wanted_to_know"

QUERY -> SELECT SELECT SUM(DATEDIFF(YEAR(till)-MONTH(till)-01,(till))) AS AMOUNT

How can I combine that queries in ONE if statement in the SELECT?
Or is it not possible and I need to work with three temp_tables?

Thanks!