Not sure specifically about MS products but if it is like everything else it will go from the highest and will not go back on itself too "fill in" deleted records. The easiest way to confirm whether the field is auto-incrementing is either to look at the table structure or to do an sql insert explicitly giving the other fields and their values but not the ID. If the ID is, as it should be - an auto-incrementing primary key, the database will insert an incremented ID for you.