第六章 数据筛选和排序

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;using System.Data.SqlClient;namespace WindowsFormsApplication1{    public partial class Form2 : Form    {              DBHelper db = new DBHelper();                DataSet ds = new DataSet();                SqlDataAdapter der = null;        public Form2()        {            InitializeComponent();        }        private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)        {        }        public void getstudent()        {            //清空原有数据            if (ds.Tables["student"] != null) {                ds.Tables["student"].Clear();                        }            string ent =@"SELECT [StudentNo] as 学号      ,[LoginPwd]  as 密码      ,[StudentName]  as 姓名      ,[Sex]       ,[GradeId]        ,[Phone]  as  电话      ,[Address] as  地址      ,[BornDate]  as 出生日期      ,[Email]  FROM [MySchool].[dbo].[Student] ";            der = new SqlDataAdapter(ent,db.Connection);            der.Fill(ds,"student");         this.dataGridView1.DataSource=ds.Tables["student"];                   }        private void Form2_Load(object sender, EventArgs e)        {            getstudent();                  }        private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)        {          //  string message = string.Format("选中了{0}节点,深度是{1}",treeView1.SelectedNode.Text,treeView1.SelectedNode.Level);          //  MessageBox.Show(message,"提示",MessageBoxButtons.OK,MessageBoxIcon.Information);                        shitu();                    }        public  void  shitu()        {          DataView dv = new DataView(ds.Tables["student"]);          string filer = "";            if(treeView1.SelectedNode.Text.Equals("S1")){                filer = "[GradeId]=1";                          }else if(treeView1.SelectedNode.Text.Equals("S2"))            {               filer = "[GradeId]=2";            }else if(treeView1.SelectedNode.Text.Equals("Y2"))            {               filer="[GradeId]=3";            }          if(treeView1.SelectedNode.Level==2){              MessageBox.Show(treeView1.SelectedNode.Level.ToString());           string gender = treeView1.SelectedNode.Tag.ToString();           int num = Convert.ToInt32(treeView1.SelectedNode.Parent.Tag);           MessageBox.Show(gender);                       filer = "GradeId="+num+" and Sex='"+gender+"'";            }            dv.RowFilter = filer;            dv.Sort = "GradeId  desc";                    this.dataGridView1.DataSource = dv;        }        private void 删除ToolStripMenuItem_Click(object sender, EventArgs e)        {            DialogResult fell;            fell = MessageBox.Show("确定要删除该学生吗?", "提示", MessageBoxButtons.YesNo, MessageBoxIcon.Information);            MessageBox.Show(fell.ToString());            if (fell == DialogResult.Yes)            {                              if (dataGridView1.SelectedRows.Count > 0)                {                                  string studentNo = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();                   MessageBox.Show(studentNo);                    try                    {                        db.OpenConnection();                        string sql = string.Format("delete  from dbo.Student where StudentNo='{0}'", studentNo);                        SqlCommand command = new SqlCommand(sql, db.Connection);                        int result = command.ExecuteNonQuery();                        MessageBox.Show(result.ToString());                        if (result == 1)                        {                            MessageBox.Show("删除成功!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);                            getstudent();                        }                    }                    catch (Exception r)                    {                        MessageBox.Show(r.Message);                        MessageBox.Show("系统出现错误!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Error);                    }                    finally                    {                        db.CloseConnection();                    }                }            }        }        private void 获得idToolStripMenuItem_Click(object sender, EventArgs e)        {            MessageBox.Show(this.dataGridView1.SelectedCells[0].Value.ToString());        }                  }        }