学生管理系统-----分层

首先建立三层：DAL(窗体)、BLL(类库)、UI(类库)和实体类Model

他们的关系是：UI引用BLL和Model，BLL引用DAL和Model，DAL引用Model，Model谁都不引用

      

登录功能：

   DAL层：（为了防止sql注入需要使用SqlParameter）

       //登录
       public bool LoginStudent(Student stu) 
       {
           bool flag = false;
           string sql = "select count(1) from Student where StudentName=@name and LoginPwd=@pwd";
           SqlParameter[] para = 
           {
           new SqlParameter("@name",stu.StudentName),
           new SqlParameter("@pwd",stu.LoginPwd)
           };
           int count=Convert.ToInt32(SQLHelper.ExecuteScalar(sql,para));
           if (count > 0)
           {
               flag = true;
           }
           return flag;
       }

   BLL层：（只做数据传递的载体）

 StudentDAL dal = new StudentDAL();
       //登录
       public bool IsLogin(Student stu) 
       {
           bool result = dal.LoginStudent(stu);
           return result;
       }

   UI层：

 private void btnLogin_Click(object sender, EventArgs e)
        {
            StudentBLL bll = new StudentBLL();
            Student stu = new Student();
            stu.StudentName = txtName.Text;
            stu.LoginPwd = txtPwd.Text;
            bool result=bll.IsLogin(stu);
            if (result)
            {
                MessageBox.Show("登录成功！");
                FrmMain frm = new FrmMain();
                this.Hide();
                frm.Show();
            }
            else
            {
                MessageBox.Show("哎哟！失败啦！");
            }
        }

效果：

             

登录成功后进入主界面

添加学生：

  DAL层：

 //添加学生
       public bool AddStudent(Student stu)
       {
           bool flag = false;
           string sql = "insert into Student values('"+stu.StudentNo+"','"+stu.LoginPwd+"','"+stu.StudentName+"','"+stu.Sex+"','"+stu.GradeId+"','"+stu.Phone+"','"+stu.Address+"','"+stu.BornDate+"','"+stu.Email+"')";
           int count = SQLHelper.ExecuteNonQuery(sql);
           if (count > 0) 
           {
               flag = true;
           }
           return flag;
       }

  BLL层：

      //添加
       public bool Add(Student stu) 
       {
           bool result = dal.AddStudent(stu);
           return result;
       }

  UI层：

 private void btnEdit_Click(object sender, EventArgs e)
        {
            stu.StudentNo = txtStudentNo.Text;
            stu.LoginPwd = txtPwd.Text;
            stu.StudentName = txtName.Text;
            stu.Sex = rbtnFemale.Checked ? "0" : "1";
            stu.GradeId = Convert.ToInt32(cboGrade.SelectedValue);
            stu.Phone = txtPhone.Text;
            stu.Address = txtAddress.Text;
            stu.BornDate = dpBirthday.Value;
            stu.Email = txtEmail.Text;      

            if (txtPwd.Text.Trim() != txtRePwd.Text.Trim())
            {
                MessageBox.Show("密码请输入一致!");
                return;
            }
            
                bool re = bll.Add(stu);
                if (re)
                {
                    MessageBox.Show("添加成功!");
                }
                else
                {
                    MessageBox.Show("添加失败!");
                }          
         }

  效果：

删除学生：

  DAL层：

 //删除学生
       public bool DeleteStudent(string StuNo) 
       {
           bool flag = false;
           string sql = "delete from Student where StudentNo=@stuno";
           SqlParameter para = new SqlParameter("stuno",StuNo);
           int count = SQLHelper.ExecuteNonQuery(sql,para);
           if (count > 0) 
           {
               flag = true;
           }
           return flag;
       }

  BLL层：

 //删除
       public bool DeleteStudent(string StuNo) 
       {
           return dal.DeleteStudent(StuNo);
       }

  UI层：

 private void 删除ToolStripMenuItem_Click(object sender, EventArgs e)
        {

            string stuno = dgvListName.SelectedRows[0].Cells["studentno"].Value.ToString();

            //获取当前选中行的索引值
            int index = dgvListName.CurrentRow.Index;

            bool result = bll.DeleteStudent(stuno);
            if (result)
            {
                MessageBox.Show("删除成功!");
                List<Student> list = bll.Gets();
                dgvListName.DataSource = list;
               
                //光标停留
                dgvListName[0, index].Selected = true;
                dgvListName.CurrentCell = dgvListName[0, index];
            }
        }

效果：

修改：

  DAL层：

 //修改
       public bool UpdateStudent(Student stu) 
       {
           bool flag = false;
           string sql = "update student set studentno=@studentno,studentname=@studentname,sex=@sex,gradeid=@gradeid where studentno=@studentno";
           SqlParameter[] paras = 
           {
           new SqlParameter("@studentname",stu.StudentName),
           new SqlParameter("@studentno",stu.StudentNo),
           new SqlParameter("@sex",stu.Sex),
           new SqlParameter("@gradeid",stu.GradeId)
           };
           int count = SQLHelper.ExecuteNonQuery(sql,paras);
           if (count > 0) 
           {
               flag = true;
           }
           return flag;
       }

  BLL层：

//修改
       public bool UpdateStudent(Student stu)
       {
           return dal.UpdateStudent(stu);
       }

  UI层：

修改需要新建一个窗体

        StudentBLL bll = new StudentBLL();
        Student stu = new Student();
        public DataGridView dgvListName = null;
        private void UpdateStudent_Load(object sender, EventArgs e)
        {
            //绑定值
            stu.StudentNo = dgvListName.SelectedRows[0].Cells["studentno"].Value.ToString();
            stu.StudentName = dgvListName.SelectedRows[0].Cells["studentname"].Value.ToString();
            stu.Sex = dgvListName.SelectedRows[0].Cells["sex"].Value.ToString();
            stu.GradeId = Convert.ToInt32(dgvListName.SelectedRows[0].Cells["gradeid"].Value);
            this.txtNo.Text = stu.StudentNo;
            this.txtName.Text = stu.StudentName;
            this.txtSex.Text = stu.Sex;
            this.txtGrade.Text = stu.GradeId.ToString();
        }

        private void btnUpdate_Click(object sender, EventArgs e)
        {
            int index = dgvListName.CurrentRow.Index;
            stu.StudentName = txtName.Text;
            stu.Sex = txtSex.Text;
            stu.StudentNo = txtNo.Text;
            bool flag = bll.UpdateStudent(stu);
            if (flag) 
            {
                MessageBox.Show("修改成功！");
                List<Student> list = bll.Gets();
                dgvListName.DataSource = list;

                dgvListName[0, index].Selected = true;
                dgvListName.CurrentCell = dgvListName[0, index];
            }
        }

     private void 修改ToolStripMenuItem_Click(object sender, EventArgs e)
        {         
            UpdateStudent up = new UpdateStudent();
            up.dgvListName = dgvListName;
            up.Show();
        }

效果：