Compare time values correctly - mysql

Question

I am having trouble comparing MySQL Time fields, I have a NOEVENTS row starting from 09:00 to 10:00 and I am trying to insert a row into another table, but I need to compare the NOEVENTS time, to the incoming Time fields. example:
I want to insert a event from 09:15 to 09:30, and another from 10:00 to 11:00, so how can I compare that? im trying this:
select count(idNOEVENTS) into existNOEVENT from NOEVENTS b where eventInitialTime && eventFinalTime between b.initialTime and b.finalTime;
if existNOEVENT>0
SET MESSAGE_TEXT = 'Error! no events allowed at this time';
The problem is when I try to insert the 09:15 to 09:30, it throws the error message shown above. Thats fine, it works, but when I try to insert the 10:00 to 11:00 event it throw the msg, and it shouldnt, how can I fix it? or compare it better?
Thanks, and sorry for my poor english.

Answer 1

You can do it this way
SELECT *
FROM noevents
WHERE (? > initialTime AND ? < finalTime)
OR (? > initialTime AND ? < finalTime)
Now don't use COUNT(*) to check for existence of a row(s). Use EXIST() instead.
That being said to give an idea this how you procedure code might look like
DELIMITER $$
CREATE PROCEDURE add_event(IN _start TIME, IN _end TIME)
BEGIN
IF EXISTS(SELECT *
FROM noevents
WHERE (_start > initialTime AND _start < finalTime)
OR (_end > initialTime AND _end < finalTime)) THEN
SIGNAL sqlstate '45000'
SET message_text = 'Error! no events allowed at this time';
ELSE
-- Do whatever you have to do to insert an event
SELECT 'Success: event added';
END IF;
END$$
DELIMITER ;
Here is SQLFiddle demo