check availability of a room with SQL

Question

I want to check if a certain room is available between a start and end date. I am doing this with a webservice function. This function gives back a list with all the reservation

Answer 1

AND has higher precedence than OR.

Change the last line to:

AND (res.DATUM_BEGIN >= @DATUM_EINDE OR res.DATUM_EINDE <= @DATUM_BEGIN)

Answer 2

  SELECT * FROM ARTICLES_RESERVERING res
  INNER JOIN ARTICLES_ZAAL roo ON res.ZAALID = roo.ID 
  WHERE roo.ID = @ZAALID
  AND  @DATUM_EINDE between res.DATUM_BEGIN and res.DATUM_EINDE

I will rather use this query as using OR is generally expensive.