How can we create users with the same email but not the same workflow? - sql-server

Question

I want to make it possible to create several users, even with the same email address as long as they do not have the same "IdWorkflow" number.
But obviously it doesn't work... result.Succeeded is always false. & all I have is that message : "User name 'test#test.com' is already taken."
What can I do...?
Register.cshtml.cs
if (ModelState.IsValid)
{
var user = new ApplicationUser { UserName = Input.Email, Email = Input.Email, IdWorkflow = Input.IdWorkflow };
var result = await _userManager.CreateAsync(user, Input.Password);
if (result.Succeeded)
{
_logger.LogInformation("User created a new account with password.");
var code = await _userManager.GenerateEmailConfirmationTokenAsync(user);
code = WebEncoders.Base64UrlEncode(Encoding.UTF8.GetBytes(code));
var callbackUrl = Url.Page(
"/Account/ConfirmEmail",
pageHandler: null,
values: new { area = "Identity", userId = user.Id, code = code, returnUrl = returnUrl },
protocol: Request.Scheme);
await _emailSender.SendEmailAsync(Input.Email, "Confirm your email",
$"Please confirm your account by <a href='{HtmlEncoder.Default.Encode(callbackUrl)}'>clicking here</a>.");
if (_userManager.Options.SignIn.RequireConfirmedAccount)
{
return RedirectToPage("RegisterConfirmation", new { email = Input.Email, returnUrl = returnUrl });
}
else
{
await _signInManager.SignInAsync(user, isPersistent: false);
return LocalRedirect(returnUrl);
}
}
foreach (var error in result.Errors)
{
ModelState.AddModelError(string.Empty, error.Description);
}
}
AspNetUsers.sql
CREATE TABLE [dbo].[AspNetUsers] (
[Id] NVARCHAR (450) NOT NULL,
[UserName] NVARCHAR (256) NULL,
[NormalizedUserName] NVARCHAR (256) NULL,
[Email] NVARCHAR (256) NULL,
[NormalizedEmail] NVARCHAR (256) NULL,
[EmailConfirmed] BIT NOT NULL,
[PasswordHash] NVARCHAR (MAX) NULL,
[SecurityStamp] NVARCHAR (MAX) NULL,
[ConcurrencyStamp] NVARCHAR (MAX) NULL,
[PhoneNumber] NVARCHAR (MAX) NULL,
[PhoneNumberConfirmed] BIT NOT NULL,
[TwoFactorEnabled] BIT NOT NULL,
[LockoutEnd] DATETIMEOFFSET (7) NULL,
[LockoutEnabled] BIT NOT NULL,
[AccessFailedCount] INT NOT NULL,
[DateCreate] DATETIME2 (7) DEFAULT ('0001-01-01T00:00:00.0000000') NOT NULL,
[DateUpdate] DATETIME2 (7) DEFAULT ('0001-01-01T00:00:00.0000000') NOT NULL,
[IdWorkflow] NVARCHAR (450) NULL,
CONSTRAINT [PK_AspNetUsers] PRIMARY KEY CLUSTERED ([Id] ASC)
);
GO
CREATE UNIQUE NONCLUSTERED INDEX [UserNameIndex]
ON [dbo].[AspNetUsers]([NormalizedUserName] ASC, [IdWorkflow] ASC) WHERE ([NormalizedUserName] IS NOT NULL);