第一学期 C#容易忘记的方法

第一学期  C#容易忘记的方法

    如何将数据加载到ListView中

    DBHelper 类中的代码

    DataGridView数据传参

    ListView数据传参

    DBHelp类的封装

2017-12-16如何将数据加载到ListView中

方法1：

　private void LoadListView()
　　{
　　　　string sql = "select * from employee";
　　　　lvEmp.Items.Clear();
　　　　SqlDataReader dr = DBHelper.ExecuteReader(sql);
　　　　while (dr.Read())
　　　　{
　　　　ListViewItem lvi = new ListViewItem(dr["Id"].ToString());
　　　　lvi.SubItems.AddRange(
　　　　new string[] {
　　　　dr[" "].ToString(),
　　　　dr[" "].ToString(),
　　　　dr[" "].ToString(),
　　　　dr[" "].ToString(),
　　　　});
　　　　lvEmp.Items.Add(lvi);
　　}
　　　　dr.Close();
　　　　DBHelper.Closecon();

　　}

方法二：

创建DBhelper类，构造方法

 

public static DataTable GetTable(string sql)
　　　{
　　　　　　DataTable dt = new DataTable();
　　　　　　SqlDataAdapter sda = new SqlDataAdapter(sql, GetConnection());
　　　　　　sda.Fill(dt);
　　　　　　return dt;
　　　}

 private void LoadListView()

  {

     string sql = "select * from employee";

     lvEmp.Items.Clear();

     DataTable dt = DBHelper.GetTable(sql);

     foreach (DataRow dr in dt.Rows)//遍历数据表中的每一行

      {

        ListViewItem lvi = new ListViewItem(dr[0].ToString());

        lvi.SubItems.AddRange(

        new string[] {

        dr[1].ToString(),

        dr[2].ToString(),

        dr[3].ToString(),

        dr[4].ToString()

      });

    lvEmp.Items.Add(lvi);

   }

    DBHelper.Closecon();

   }

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Configuration;
using System.Data.SqlClient;

namespace 机试7
{
public class DBHelper
{
public static string conStr = "server=.;database=CarsStore;uid=sa;pwd=sa";
static SqlConnection con = null;
#region 获取连接
public static SqlConnection GetConnection()
{
if (con == null || con.ConnectionString == "")
{
con = new SqlConnection(conStr);
}
return con;
}
#endregion

#region 打开连接
//打开连接
public static void OpenConnection()
{
if (con.State == ConnectionState.Closed)
{
con.Open();
}
}
#endregion

#region 关闭连接
//关闭连接
public static void CloseConnection()
{
if (con.State == ConnectionState.Open)
{
con.Close();
}
}
#endregion

public static int ExecuteNonQuery(string sql,
params SqlParameter []para)
{
SqlConnection con = GetConnection();
OpenConnection();
SqlCommand com = new SqlCommand(sql,con);
com.Parameters.AddRange(para);
int n = com.ExecuteNonQuery();
CloseConnection();
return n;

}

public static SqlDataReader ExecuteReader(string sql,
params SqlParameter[]para)
{
SqlConnection con = GetConnection();
OpenConnection();
SqlCommand com = new SqlCommand(sql, con);
com.Parameters.AddRange(para);
SqlDataReader dr = com.ExecuteReader();
return dr;

}

}
}

 DataGridView数据传参

 

 

DataGridView 的单击事件

private void dgvTicket_Click(object sender, EventArgs e)
{

if(dgvTicket.SelectedRows.Count>0)

{

txtLeaveCity.Text = dgvTicket.SelectedRows[0].Cells["Column3"].Value.ToString();
txtArriveCity.Text = dgvTicket.SelectedRows[0].Cells["Column4"].Value.ToString();
txtLeaveTime.Text = dgvTicket.SelectedRows[0].Cells["Column5"].Value.ToString();
txtSeatPrice.Text = dgvTicket.SelectedRows[0].Cells["Column6"].Value.ToString();
txtBedPrice.Text = dgvTicket.SelectedRows[0].Cells["Column7"].Value.ToString();

}

}

ListView数据传参

listView的单击事件

private void lvTicket_Click(object sender, EventArgs e)
{
if(lvTicket.SelectedItems.Count>0)
{

txtLeaveCity.text=lvTicket.SelectedItems[0].SubItems[2].Text;

txtArriveCity.text=lvTicket.SelectedItems[0].SubItems[3].Text;

txtLeaveTime.text=lvTicket.SelectedItems[0].SubItems[4].Text;

txtSeatPrice.text=lvTicket.SelectedItems[0].SubItems[5].Text;

txtBedPrice.text=lvTicket.SelectedItems[0].SubItems[6].Text;
}

}

 

 DBHelp类的封装

using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Data;

namespace 机试12
{
   public  class DBHelp
    {
        public static string conStr = "server=.;database=TicketManager;uid=sa;pwd=sa;";
        public static SqlConnection con = null;
        public static SqlConnection GetConnection()
        {
            if (con == null || con.ConnectionString == "")
            {
                con = new SqlConnection(conStr);
            }
            return con;
        }

        public static void OpenConnection()
        {
            if (con.State == ConnectionState.Closed)
            {
                con.Open();
            }
        }
   public static void CloseConnection()
        {
            if (con.State == ConnectionState.Open)
            {
                con.Close();
            }
        }
     

        public static int ExecuteNonQuery(string sql)
        {
            SqlConnection con = GetConnection();
            OpenConnection();
            SqlCommand com = new SqlCommand(sql, con);
            int n = com.ExecuteNonQuery();
            CloseConnection();
            return n;

        }
        public static SqlDataReader ExecuteReader(string sql )
        {
            SqlConnection con = GetConnection();
            OpenConnection();
            SqlCommand com = new SqlCommand(sql, con);
            SqlDataReader dr = com.ExecuteReader();
            return dr;

        }
    }
}