3章 上机习题

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 Form1 : Form    {        public Form1()        {            InitializeComponent();        }        private void Form1_Load(object sender, EventArgs e)        {   g();                    }        private void toolStripButton1_Click(object sender, EventArgs e)        {            Form2 s = new Form2();                       s.Show();        }        private void button1_Click(object sender, EventArgs e)        {            this.listView1.View = View.LargeIcon;        }        private void button2_Click(object sender, EventArgs e)        {            this.listView1.View = View.SmallIcon;        }        private void button3_Click(object sender, EventArgs e)        {            this.listView1.View = View.Details;        }        public bool g() {            if (listView1.Items.Count>0)            {                listView1.Items.Clear();                        }            DBHelper s = new DBHelper();            try            {                s.OpenConnection();                string sql = @"SELECT TOP 1000 [StudentNo]      ,[LoginPwd]      ,[StudentName]      ,[Sex]      ,[GradeId]      ,[Phone]      ,[Address]      ,[BornDate]      ,[Email]       FROM [MySchool].[dbo].[Student] WHERE StudentName like '%" + this.textBox1.Text + "%' ";                SqlCommand comm = new SqlCommand(sql, s.Connection);                SqlDataReader r = comm.ExecuteReader();                while (r.Read())                {                    ListViewItem i = new ListViewItem(r["StudentName"].ToString(), 0);                    i.SubItems.AddRange(new string[] { r["Phone"].ToString(), r["Sex"].ToString(), r["Email"].ToString() });                    this.listView1.Items.Add(i);                }                if(!r.HasRows){                    MessageBox.Show("没有要查找的记录","提示",MessageBoxButtons.OK,MessageBoxIcon.Information);                }                r.Close();            }            catch (Exception e)            {                Console.WriteLine(e);                            }            return true;        }        private void listView1_SelectedIndexChanged(object sender, EventArgs e)        {        }        private void chazhao_Click(object sender, EventArgs e)        {            g();        }          }    }using System;using System.Collections.Generic;using System.Text;using System.Data.SqlClient;using System.Data;namespace WindowsFormsApplication1{    /// <summary>    /// 此类维护数据库连接字符串，和 Connection 对象    /// </summary>  public  class DBHelper    {        // 数据库连接字符串        private string connString = @"Data Source=.;Initial Catalog=MySchool;Integrated Security=True";        // 数据库连接 Connection 对象        private SqlConnection connection;        /// <summary>        /// Connection对象        /// </summary>        public SqlConnection Connection        {            get            {                if (connection == null)                {                    connection = new SqlConnection(connString);                }                return connection;            }                    }        /// <summary>        /// 打开数据库连接        /// </summary>        public void OpenConnection()        {            if (Connection.State == ConnectionState.Closed)            {                Connection.Open();            }            else if (Connection.State == ConnectionState.Broken)            {                Connection.Close();                Connection.Open();            }        }        /// <summary>        /// 关闭数据库连接        /// </summary>        public void CloseConnection()        {            if (Connection.State == ConnectionState.Open || Connection.State == ConnectionState.Broken)            {                Connection.Close();            }        }    }}