Your form label says "search by name, extension no or room number". Presume you mean AND because this will never work unless
- each user provides EACH value, correctly separated (e.g. by comma)
- or each user enters ,, when the middle value isn't provided (as in Con,,10) AND you trap for no value (,,)
- and each user always enters values in the correct order
- and you allow for partial matches by using the LIKE operator
Either employ a search form as suggested in the link, or since you only have 3 fields, use some other design approach such as 3 unbound textboxes to enter values. Validate which ones have data and build a sql statement in code. You cannot use a stored query to reference form controls when it's possible that one or more controls don't have values. If you did, empty controls will usually result in no records. If you go this route you can get help here once you've built the form.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.