add in the check user already exist.

CarParkValidationAPI/Interface/IAdminUser.cs

@@ -11,6 +11,7 @@ namespace CarParkValidationAPI.Interface
     public interface IAdminUser
     {
         Task<ResultModel<List<AdminUserViewDto>>> LoadAdminUserAsync(bool OnlyActive);
+        Task<ResultModel<bool>> CheckAdminUserByStaffLinkNoAsync(string staffLinkNo);
         Task<ResultModel<int>> SaveAdminUserAsync(AdminUserDto item);
         Task<ResultModel<AdminUserDto>> LoadAdminUserByIdAsync(int id);
         Task<ResultModel<bool>> DeleteAdminUserAsync(int id);