Web层 
addStudent.aspx.cs
protected void btnAdd_Click(object sender, EventArgs e)
    {
        StudentInfo info = new StudentInfo();
        info.Name = txtName.Text;
    ......
        if (StudentBLL.AddStudent(info))
        {
            JScript.AlertAndRedirect("添加成功！", "ManageStudent.aspx");
        }
    }

addTeacher.aspx.cs
protected void btnAdd_Click(object sender, EventArgs e)
    {
        TeacherInfo info = new TeacherInfo();
        info.Name = txtName.Text;
    ......
        if (TeacherBLL.AddTeacher(info))
        {
            JScript.AlertAndRedirect("添加成功！", "ManageTeacher.aspx");
        }
    }

BLL层
(StudentBLL.cs)
        public static bool AddStudent(StudentInfo info)
        {
         if (instance.AddStudent(info))
                return true;
        else
                return false;
        }
(TeacherBLL.cs)
        public static bool AddTeacher(TeacherInfo info)
        {
         if (instance.AddTeacher(info))
                return true;
        else
                return false;
        }
DAL层
(StudentDAL.cs)
        public bool AddStudent(StudentInfo info)
        {
        
            StringBuilder buffer = new StringBuilder();
            buffer.Append("insert into People(Flag,Name,Sex) Values (@Flag,@Name,@Sex)");
            SqlParameter[] parameters = {
                    new SqlParameter("@Flag",SqlDbType.Int,4)...};
            parameters[0].Value = 1;
        ...
            SqlDbHelper db = new SqlDbHelper();
            return db.ExecuteNonQuery(buffer.ToString(), CommandType.Text, parameters) > 0;
        }
(TeacherDAL.cs)
    public bool AddTeacher(TeacherInfo info)
        {
            StringBuilder buffer = new StringBuilder();
            buffer.Append("insert into People(Flag,Name,Sex) Values (@Flag,@Name,@Sex)");
            SqlParameter[] parameters = {
                    new SqlParameter("@Flag",SqlDbType.Int,4)...};
            parameters[0].Value = 2;
        ...
            SqlDbHelper db = new SqlDbHelper();
            return db.ExecuteNonQuery(buffer.ToString(), CommandType.Text, parameters) > 0;
        }
DBUtility层
StudentInfo.cs
...
TeacherInfo.cs
...