Write a trigger to prevent creating two Booking__c records for the same Room__c with overlapping Start_Date__c and End_Date__c.

trigger BookingTrigger on Booking__c (before insert, before update) {
    Set<Id> rooms = new Set<Id>();
    for (Booking__c b : Trigger.new) rooms.add(b.Room__c);
    List<Booking__c> existing = [SELECT Id, Room__c, Start_Date__c, End_Date__c FROM Booking__c
                                 WHERE Room__c IN :rooms AND Id NOT IN :Trigger.new];
    for (Booking__c b : Trigger.new) {
        for (Booking__c e : existing) {
            if (e.Room__c == b.Room__c && b.Start_Date__c < e.End_Date__c && b.End_Date__c > e.Start_Date__c)
                b.addError('Room is already booked for these dates.');
        }
        for (Booking__c o : Trigger.new) {
            if (o != b && o.Room__c == b.Room__c && b.Start_Date__c < o.End_Date__c && b.End_Date__c > o.Start_Date__c)
                b.addError('Overlaps another booking in this request.');
        }
    }
}