MVC3怎样设置ntext字段？

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ComponentModel.DataAnnotations;
 
namespace CloudOne.Models
{
    public class Blog
    {
        public int BlogID { get; set; }
        public int CategoryID { get; set; }
        [MaxLength(70)]
        [Required]
        public string BlogTitle { get; set; }
        [Column(TypeName="ntext")]
        [MaxLength]
        public string BlogContent { get; set; }
    }
}