SELECT
  *
FROM
  `fao-maps.idmc.vw_global_internal_displacement_database_m49`
WHERE
   (Hazard_Category = @hazard OR "All" = @hazard)
OR 
    (Hazard_Type = @hazard or "All" = @hazard)

OR (@hazard="Others" and (Hazard_Category is null or Hazard_Type is null ));