migrate datatable from database to Dbset

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C#

SQL-Server

entity-framework

Here,
In my sqlserver database has a table name 'dbo.UserRole' and i want to populate as DBset in my DbContext.
but when i add a DbContext as like

public class DbContext:DbContext
    {
        public DbSet <User> Users{ get; set; }
        public DbSet <UserRole> UserRoles { get; set; }
    }

'User' and 'UserRole' is model class.

then a table name is "UserRoles1", add as new datatable in database.
but i want to use Existing "UserRoles" table.