/// <summary>
 /// Returns a value indicating whether the day exists.
 /// </summary>
 /// <param name="id">The identifier.</param>
 /// <param name="ctx">The entity container.</param>
 /// <returns>The day exists.</returns>
 public bool DayExists(Guid id, BzsEntityContainer ctx)
 {
     return ctx.DaySet.Any(f => f.Id == id);
 }
 /// <summary>
 /// Returns a value indicating whether the room exists.
 /// </summary>
 /// <param name="id">The identifier.</param>
 /// <param name="ctx">The entity container.</param>
 /// <returns>The room exists.</returns>
 public bool RoomExists(Guid id, BzsEntityContainer ctx)
 {
     return ctx.RoomSet.Any(f => f.Id == id);
 }
 /// <summary>
 /// Returns a value indicating whether the teacher exists.
 /// </summary>
 /// <param name="id">The identifier.</param>
 /// <param name="ctx">The entity container.</param>
 /// <returns>The teacher exists.</returns>
 public bool TeacherExists(Guid id, BzsEntityContainer ctx)
 {
     return ctx.TeacherSet.Any(f => f.Id == id);
 }