Resolve error when deleting an account connected to a provider (#1580)

src/Sql/Sql.sqlproj

@@ -74,6 +74,7 @@
     <Build Include="dbo\Stored Procedures\Event_ReadPageByProviderIdActingUserId.sql" />
     <Build Include="dbo\Stored Procedures\ProviderOrganization_ReadByOrganizationId.sql" />
     <Build Include="dbo\Stored Procedures\ProviderUserProviderOrganizationDetails_ReadByUserIdStatus.sql" />
+    <Build Include="dbo\Stored Procedures\ProviderUser_ReadCountByOnlyOwner.sql" />
     <Build Include="dbo\Stored Procedures\SsoConfig_Create.sql" />
     <Build Include="dbo\Stored Procedures\SsoConfig_ReadByIdentifier.sql" />
     <Build Include="dbo\Stored Procedures\SsoConfig_ReadByOrganizationId.sql" />

src/Sql/dbo/Stored Procedures/ProviderUser_ReadCountByOnlyOwner.sql

@@ -0,0 +1,25 @@
+CREATE PROCEDURE [dbo].[ProviderUser_ReadCountByOnlyOwner]
+    @UserId UNIQUEIDENTIFIER
+AS
+BEGIN
+    SET NOCOUNT ON
+
+    ;WITH [OwnerCountCTE] AS
+    (
+        SELECT
+            PU.[UserId],
+            COUNT(1) OVER (PARTITION BY PU.[ProviderId]) [ConfirmedOwnerCount]
+        FROM
+            [dbo].[ProviderUser] PU
+        WHERE
+            PU.[Type] = 0 -- 0 = ProviderAdmin
+            AND PU.[Status] = 2 -- 2 = Confirmed
+    )
+    SELECT
+        COUNT(1)
+    FROM
+        [OwnerCountCTE] OC
+    WHERE
+        OC.[UserId] = @UserId
+        AND OC.[ConfirmedOwnerCount] = 1
+END

src/Sql/dbo/Stored Procedures/User_DeleteById.sql

@@ -65,6 +65,13 @@ BEGIN
     WHERE
         [UserId] = @Id
 
+    -- Delete provider users
+    DELETE
+    FROM
+        [dbo].[ProviderUser]
+    WHERE
+        [UserId] = @Id
+
     -- Delete U2F logins
     DELETE
     FROM