Expanding Hierachy With Multiple Parents

I have a user assigned multiple roles and a role can be inherited from
multiple parents (see below). How do I answer such questions as "How
many roles does the user belongs to?"

I answered the above questions by using .NET but I think it can be
more efficient by using just SQL. I would appreciate if you can give
me an answer.

Thank you.


CREATE TABLE [dbo].[tb_User] (
[Id] [int] IDENTITY (1, 1) NOT NULL PRIMARY KEY,
[Name] nvarchar(99) NOT NULL UNIQUE,
[Password] nvarchar(99) NOT NULL,
) ON [PRIMARY]
GO

CREATE TABLE [dbo].[tb_Role] (
[Id] [int] IDENTITY (1, 1) NOT NULL PRIMARY KEY,
[Name] nvarchar(99) NOT NULL UNIQUE,
) ON [PRIMARY]
GO

CREATE TABLE [dbo].[tb_User_Role] (
[UserId] [int] NOT NULL ,
[RoleId] [int] NOT NULL,
) ON [PRIMARY]
GO


ALTER TABLE [dbo].[tb_User_Role] WITH NOCHECK ADD
CONSTRAINT [PK_tb_User_Role] PRIMARY KEY CLUSTERED
(
[UserId],
[RoleId]
) ON [PRIMARY]
GO

CREATE TABLE [dbo].[tb_Parent_Role] (
[RoleId] [int] NOT NULL ,
[ParentRoleId] [int] NOT NULL ,
) ON [PRIMARY]
GO

ALTER TABLE [dbo].[tb_Parent_Role] WITH NOCHECK ADD
CONSTRAINT [PK_tb_Parent_Role] PRIMARY KEY CLUSTERED
(
[RoleId],
[ParentRoleId]
) ON [PRIMARY]
GO