为sqlDataSource添加的SelectParameters为何报错？

代码：
this.SqlDS.SelectCommand = "SELECT * FROM [USER] where [USER_ID] = @USER_ID and [TYPE_ID] = @TYPE_ID";
this.SqlDS.SelectParameters["@USER_ID"].DefaultValue = "1";
this.SqlDS.SelectParameters["@TYPE_ID"].DefaultValue = "1";

错误提示为：
Input string was not in a correct format.
TYPE_ID、USER_ID字段是int型,但SelectParameters的DefaultValue 只接受字符型。会不会是这个原因？如何解决？

[解决方法]

this.SqlDS.SelectCommand = "SELECT * FROM [USER] where [USER_ID] = @USER_ID and [TYPE_ID] = @TYPE_ID";
SqlParameter[] parameters = {
                             new SqlParameter("@USER_ID", SqlDbType.Int,8),
           new SqlParameter("@TYPE_ID", SqlDbType.Int,8)}
parameters[0].Value = 1;
parameters[1].Value = 1;
foreach (SqlParameter parm in parameters)
{
    SqlDS.Parameters.Add(parm);
}