03课后5

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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 WindowsFormsApplication2{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }               public bool chakan()        {            if (listView1.Items.Count > 0)            {                listView1.Items.Clear();            }                 DBHelper dbhelper = new DBHelper();                try                {                    dbhelper.OpenConnection();                    string sql2 =@" SELECT TOP 1000 [Id]      ,[Name]      ,[Type]      ,[Number]      ,[Price]  FROM [shangpin].[dbo].[Table_1] where  type like '%"+this.comboBox1.Text+"%'";                    SqlCommand comm = new SqlCommand(sql2, dbhelper.Connection);                    SqlDataReader reader = comm.ExecuteReader();                    while (reader.Read())                    {                        ListViewItem liv1 = new ListViewItem(reader["Name"].ToString());                        liv1.SubItems.AddRange(new string[] { reader["Type"].ToString(), reader["Number"].ToString(), reader["Price"].ToString() });                        this.listView1.Items.Add(liv1);                    }                }                catch (Exception ex)                {                    Console.WriteLine(ex.Message);                    return false;                }                finally                {                    dbhelper.CloseConnection();                }            return true;            }              private void button1_Click(object sender, EventArgs e)        {            chakan();        }        }    }

using System;using System.Collections.Generic;using System.Text;using System.Data.SqlClient;using System.Data;namespace WindowsFormsApplication2{    /// <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();            }        }    }}

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