C# 学习笔记之增删改查操作

因为之前有个CSDN的账号但是后来账号丢了，于是只能另起炉灶，今天总有找回了丢失已久的登录秘密，不知道有没有办法将两个博客合并，只能手动复制黏贴以前的博文过来。。。悲惨

源地址：http://blog.csdn.net/sxfenglei/article/details/5431264 该博客不再用了

现在看看当年写的代码 真幼稚呵呵 转过来纪念下当年的稚嫩，哈哈

/// <summary> ­
/// 对话框返回值 ­
/// ­
///这是一个退出按键的方法，用来确定用户是否真的要退出 ­
/// </summary> ­
        private void 退出ToolStripMenuItem_Click(object sender, EventArgs e) ­
        { ­
            //定义 DialogResult 变量 用以存储对话框返回值 ­
            DialogResult exitForm; ­
            //对话框 ­
            exitForm = MessageBox.Show("冯磊老大您确定要离开我吗？","退出系统",MessageBoxButtons.OKCancel,MessageBoxIcon.Information); ­
            //判断 ­
            if (exitForm == DialogResult.OK)   //使用 DialogResult 属性判断该按钮的返回值是否为 "确定" ­
            { ­
                Application.Exit();//退出系统 ­
            } ­
        } ­
/// <summary> ­
/// 创建 DBManager 类 ­
/// ­
/// 在 DBManager 类中创建数据库连接 ­
/// </summary> ­
  class DBManager ­
   { ­
    //连接数据库字符串 和 实例化 connection 对象 ­
    private static string sqlconString = "Data Source=ASUS//SQLEXPRESS;Initial Catalog=MyDB;Integrated Security=True"; ­
    public static SqlConnection con = new SqlConnection(sqlconString); ­
   } ­
/// <summary> ­
/// 创建 User 类 ­
/// ­
/// 在 User 类中创建 用于存储交换的变量 ­
/// </summary> ­
  class User ­
   { ­
    public string userID = ""; ­
    public string userName = ""; ­
    public string userAge = ""; ­
    public string userGongZi = ""; ­
    public string userJiGuan = ""; ­
   } ­
/// <summary> ­
        /// ExecuteScalar()方法 返回单个值 ­
         ­
        /// 核心 SELECT COUNT(*) FROM Student ­
        /// 核心 com.ExecuteScalar(); ­
/// </summary> ­
//定义数据库连接字符串 和 connection 对象 ­
string sqlString = "Data Source=ASUS//SQLEXPRESS;Initial Catalog=MySchool;Integrated Security=True"; ­
SqlConnection con = new SqlConnection(sqlString); ­
//打开数据库 ­
con.Open(); ­
//拼SQL语句 和 创建 command 对象 ­
string sql = "SELECT COUNT(*) FROM Student "; ­
SqlCommand com = new SqlCommand(sql,con); ­
// 执行 SQL 查询 使用ExecuteScaler()方法 返回一个读取值 ­
int num = (int)com.ExecuteScalar(); ­
//将返回值格式化后存入变量中 后输出 ­
string message = string.Format("Student表中共有{0}条学员信息！", num); ­
MessageBox.Show(message, "查询结果", MessageBoxButtons.OK, MessageBoxIcon.Information);//然后将该变量输出 ­
//关闭数据库 ­
con.Close(); ­
/// <summary> ­
        ///  将数据加载到 comboBox 控件中 ­
         ­
        /// 核心 select studentName from student ­
        /// 核心 SqlDataReader dataReader = com.ExecuteReader(); ­
        /// 核心 string studentName = ""; ­
        /// 核心 while (dataReader.Read()){ ­
        /// 核心  studentName = (string)dataReader[0]; ­
        /// 核心 comboBox1.Items.Add(studentName); ­
        /// 核心 } ­
/// </summary> ­
            //定义数据库字符 和 connection 对象 ­
            string sqlString = "Data Source=ASUS//SQLEXPRESS;Initial Catalog=MySchool;Integrated Security=True"; ­
            SqlConnection con = new SqlConnection(sqlString); ­
            //定义sql语句 和 command 对象 ­
            string sql = "select studentName from student"; ­
            SqlCommand com = new SqlCommand(sql, con); ­
            //打开数据库 ­
            con.Open(); ­
            //执行sql读取 使用dataReader对象 ­
            SqlDataReader dataReader = com.ExecuteReader(); ­
            //循环读取每一条数据 添加到comboBox1 中 ­
            string studentName = "";//将每条读取存入这个变量 用以每次想comboBox1中添加 ­
            while (dataReader.Read()) ­
            { ­
                studentName = (string)dataReader[0];//从第0项开始读取 ­
                comboBox1.Items.Add(studentName);//添加每条读取到 comboBox1 中 ­
            } ­
            //关闭读取 和 数据库 ­
            dataReader.Close(); ­
            con.Close(); ­
/// <summary> ­
        /// 将数据加载到 listView 控件中 ­
         ­
        /// 核心 SqlDataReader dataReader = com.ExecuteReader(); ­
        /// 核心 string id = ""; ­
        /// 核心 string adminUser = ""; ­
        /// 核心 string adminPwd = ""; ­
        /// 核心 while (dataReader.Read()){ ­
        /// 核心 id = dataReader["adminId"].ToString(); ­
        /// 核心 adminUser = dataReader["LoginId"].ToString(); ­
        /// 核心 adminPwd = dataReader["LoginPwd"].ToString(); ­
        /// 核心 ListViewItem liv = new ListViewItem(adminUser); ­
        /// 核心 liv.Tag = (int)dataReader["adminId"]; ­
        /// 核心 listView1.Items.Add(liv); ­
        /// 核心 liv.SubItems.AddRange(new string[] { adminPwd }); ­
        /// 核心 } ­
/// </summary> ­
   ­
  private void FillListView() ­
        { ­
   //清空listview   ­
            listView1.Items.Clear(); ­
            //定义数据库字符 和 connection 对象 ­
            string sqlconString = "Data Source=ASUS//SQLEXPRESS;Initial Catalog=MySchool;Integrated Security=True"; ­
            SqlConnection con = new SqlConnection(sqlconString);//上面定义过 ­
            //拼SQL 和 command 对象 ­
            string sql = "select * from admin";//上面定义过 ­
            SqlCommand com = new SqlCommand(sql, con);//上面定义过 ­
            con.Open(); ­
            //执行SQL语句 ­
            SqlDataReader dataReader = com.ExecuteReader(); ­
            //定义存储变量 ­
            string id = ""; ­
            string adminUser = ""; ­
            string adminPwd = ""; ­
            //循环读取数据库 数据 然后存入变量中 ­
            while (dataReader.Read()) ­
            { ­
                //将数据库中的数据读取到变量中 ­
                id = dataReader["adminId"].ToString();//拿到ID ­
                adminUser = dataReader["LoginId"].ToString(); ­
                adminPwd = dataReader["LoginPwd"].ToString(); ­
                //创建 ListView 项 ­
                ListViewItem liv = new ListViewItem(adminUser);//将 adminUser 加载到第一项中 ­
                liv.Tag = (int)dataReader["adminId"]; ­
                listView1.Items.Add(liv);//向listView1中添加一个新项 ­
                liv.SubItems.AddRange(new string[] { adminPwd });//将剩余项 adminPwd 添加到listView1中 ­
            } ­
            dataReader.Close(); ­
            con.Close(); ­
        }     ­
/// <summary> ­
  /// 单击 listView 时 将本行数据存入 user 类中的变量中 ­
        /// 核心 定义 user 类 ­
        /// 核心 使用 listView1.SelectedItems[0].SubItems[1].Text.ToString(); 拿到数据 并存入user 类中(需要实例化) ­
/// </summary> ­
        private void listView1_Click(object sender, EventArgs e) ­
        { ­
            //实例化 User 类 ­
            User us = new User(); ­
            //将鼠标点击的 listView 行的数据存入 user 类中的变量中 ­
            us.userName = listView1.SelectedItems[0].SubItems[1].Text.ToString(); ­
            us.userAge  = listView1.SelectedItems[0].SubItems[2].Text.ToString(); ­
            us.userGongZi = listView1.SelectedItems[0].SubItems[3].Text.ToString(); ­
            us.userJiGuan = listView1.SelectedItems[0].SubItems[4].Text.ToString(); ­
            //将 user类中的数据在放到 textBox 控件中 ­
            txtName.Text = us.userName; ­
            txtAge.Text = us.userAge; ­
            txtGongZi.Text = us.userGongZi; ­
            txtJiGuan.Text = us.userJiGuan; ­
        } ­
/// <summary> ­
        ///  增 ­
         ­
        /// 核心 string sql = string.Format("insert into admin (LoginId,LoginPwd) values ('{0}','{1}')",textBox1.Text,textBox2.Text); ­
        /// 核心 int num =com.ExecuteNonQuery(); ­
/// </summary> ­
   //判断非空 ­
            if(textBox1.Text.Trim()=="") ­
            { ­
                MessageBox.Show("冯磊老大你叫啥？"); ­
                textBox1.Focus();//得到焦点 ­
                return;//如果为空则返回空 即结束 ­
            }else if(textBox2.Text.Trim()=="") ­
            { ­
                MessageBox.Show("冯磊老大告诉我密码？"); ­
                textBox2.Focus(); ­
                return; ­
            } ­
            //定义数据库连接 和 connection 对象 ­
            string sqlconString = "Data Source=ASUS//SQLEXPRESS;Initial Catalog=MySchool;Integrated Security=True"; ­
            SqlConnection con = new SqlConnection(sqlconString ); ­
            //拼SQL 和 command 对象 ­
            string sql = string.Format("insert into admin (LoginId,LoginPwd) values ('{0}','{1}')",textBox1.Text,textBox2.Text); ­
            SqlCommand com = new SqlCommand(sql,con ); ­
            con.Open(); ­
            //添加数据到数据库 使用ExecutenNonQuery方法 ­
            int num =com.ExecuteNonQuery(); ­
            //如果添加成功侧提示 ­
            if (num==1) ­
            { ­
                MessageBox.Show("冯磊老大添加成功！"); ­
            } ­
            else { ­
                MessageBox.Show("哦哦~~冯磊老大添加失败！","",MessageBoxButtons.OK,MessageBoxIcon.Error); ­
            } ­
            con.Close(); ­
   //在加载 一遍 listView 可以将创建的listView 抽成方法 如 fillListView(); ­
   fillListView(); ­
/// <summary> ­
        ///  删 ­
         ­
        /// 核心 if(listView1.SelectedItems.Count==0) ­
        /// 核心 string sql = string.Format("delete from admin where AdminId='{0}'",(int)listView1.SelectedItems[0].Tag); ­
        /// 核心 int test = com.ExecuteNonQuery(); ­
/// </summary> ­
   //确保用户选择了一个学员才执行修改操作 ­
            if(listView1.SelectedItems.Count==0) ­
            { ­
                MessageBox.Show("冯磊老大你不告诉我删除那个我怎么删"); ­
                return; ­
            }else{ ­
                 ­
                //定义数据库连接字符串 和 connection 对象 ­
                string sqlconString = "Data Source=ASUS//SQLEXPRESS;Initial Catalog=MySchool;Integrated Security=True"; ­
                SqlConnection con = new SqlConnection(sqlconString); ­
                //拿ID ­
                string sql = string.Format("delete from admin where AdminId='{0}'",(int)listView1.SelectedItems[0].Tag); ­
                SqlCommand com = new SqlCommand(sql,con); ­
                con.Open(); ­
                //执行SQL ­
                 int test = com.ExecuteNonQuery(); ­
                //提示删除成功与否 ­
                 if (test > 0) ­
                 { ­
                     MessageBox.Show("冯磊老大我成功的给你灭了它！"); ­
                 } ­
                 else { ­
                     MessageBox.Show("冯磊老大我灭它失败！"); ­
                 } ­
                con.Close(); ­
            } ­
            /* listView */ ­
            FillListView();//加载FillListView(); ­
/// <summary> ­
  /// 右键 删除 ­
   ­
  /// 核心 listView1.SelectedItems[0].Tag.ToString() ­
/// </summary> ­
   DBManager.con.Open(); ­
            string sql = string.Format("delete from yuangong where id='{0}'",listView1.SelectedItems[0].Tag.ToString());//listView1.SelectedItems[0].Tag.ToString();  //拿到ID ­
            SqlCommand com = new SqlCommand(sql,DBManager.con); ­
            int shanChu = com.ExecuteNonQuery(); ­
            DBManager.con.Close(); ­
   /* listView */ ­
            FillListView();//加载FillListView(); ­
/// <summary> ­
        ///  改 ­
         ­
        /// 核心 (int)listView1.SelectedItems[0].Tag ­
        /// 核心 update YuanGong set name='{0}',age='{1}',gongzi='{2}',jiguan='{3}' where id={4} ­
        /// 核心 int Run = com.ExecuteNonQuery(); ­
/// </summary> ­
   SqlConnection sql = string.Format("update YuanGong set name='{0}',age='{1}',gongzi='{2}',jiguan='{3}' where id={4}", txtName.Text, txtAge.Text, txtGongZi.Text, txtJiGuan.Text, (int)listView1.SelectedItems[0].Tag); ­
   SqlCommand com = new SqlCommand(sql, DBManager.con); ­
   DBManager.con.Open(); ­
   int Run = com.ExecuteNonQuery(); ­
   if (Run == 1) ­
   { ­
    DBManager.con.Close(); ­
    FillListView(); ­
   } ­
   else ­
   { ­
    MessageBox.Show("冯磊老大修改失败！", "提示框", MessageBoxButtons.OK, MessageBoxIcon.Error); ­
    DBManager.con.Close(); ­
   } ­
/// <summary> ­
        ///  查 ­
         ­
        /// 核心 listView1.Items.Clear(); ­
        /// 核心 if (!datareader.HasRows) ­
        /// 核心 SqlDataReader datareader = com.ExecuteReader(); ­
/// </summary> ­
   listView1.Items.Clear(); ­
   ­
   string id = ""; ­
   string name = ""; ­
   string age = ""; ­
   string gongzi = ""; ­
   string jiguan = ""; ­
   sql = string.Format("select * from yuangong where name='{0}' or age='{1}' or gongzi='{2}' or jiguan='{3}'", txtName.Text, txtAge.Text, txtGongZi.Text, txtJiGuan.Text); ­
   com = new SqlCommand(sql, DBManager.con); ­
   SqlDataReader datareader = com.ExecuteReader(); ­
   if (!datareader.HasRows) ­
   { ­
    MessageBox.Show("哦哦~~~冯磊老大没有在国防部查到你要的数据!"); ­
    datareader.Close(); ­
    DBManager.con.Close(); ­
    return; ­
   } ­
   else { ­
    while(datareader.Read()) ­
    { ­
     id=datareader["ID"].ToString(); ­
     name=datareader["name"].ToString(); ­
     age=datareader["age"].ToString(); ­
     gongzi=datareader["gongzi"].ToString(); ­
     jiguan=datareader["jiguan"].ToString(); ­
     ListViewItem liv = new ListViewItem(id); ­
     liv.Tag=(int)datareader["ID"]; ­
     listView1.Items.Add(liv); ­
     liv.SubItems.AddRange(new string []{name,age,gongzi,jiguan}); ­
    } ­
    datareader.Close(); ­
    DBManager.con.Close(); ­
   } ­
//============================================================================================
MessageBox.Show(listView1.SelectedItems[0].Tag.ToString());  //拿到ID ­
MessageBox.Show(listView1.SelectedItems[0].SubItems[0].Text);  //拿到第一列的单元格的值 ­
//============================================================================================
/// <summary> ­
/// 创建 全局变量 ­
/// </summary> ­
        //实例化 dataSet 和 声明 dataAdapter ­
        DataSet dataSet = new DataSet(); ­
        SqlDataAdapter dataAdapter; ­
        //声明字符 ­
        string sql =""; ­
         ­
         ­
         ­
         ­
/// <summary> ­
/// 创建 fillDataGridView方法 ­
/// </summary> ­
        private void fillDataGridView() ­
        { ­
            //拼基本 SQL 语句 ­
            sql = "select id as 编号,name as 姓名,age as 年龄,gongzi as 工资,jiguan as 籍贯 from yuangong "; ­
            //实例化 dataAdapter ­
            dataAdapter = new SqlDataAdapter(sql, DBManager.con); ­
            //填充 dataSet ­
            dataAdapter.Fill(dataSet, "yuanGong"); ­
            //将数据绑定到 dataGridView中 ­
            dataGridView1.DataSource = dataSet.Tables["yuanGong"]; ­
        } ­
         ­
         ­
         ­
         ­
/// <summary> ­
/// 筛选 数据 ­
/// </summary> ­
            //刷新基本 SQL 语句 ­
            sql = "select id as 编号,name as 姓名,age as 年龄,gongzi as 工资,jiguan as 籍贯 from yuanGong "; ­
            //拼接 条件SQL 语句 ­
            switch(comboBox1.Text) ­
            { ­
                case "全部": ­
                    break; ­
                case "河南": ­
                    sql = sql + "where  jiguan='河南'"; ­
                    break; ­
                case "浙江": ­
                    sql = sql + "where jiguan='浙江'"; ­
                    break; ­
                case "陕西": ­
                    sql = sql + "where jiguan='陕西'"; ­
                    break; ­
                case "河北": ­
                    sql = sql + "where jiguan='河北'"; ­
                    break; ­
                case "青岛": ­
                    sql = sql + "where jiguan='青岛'"; ­
                    break; ­
            } ­
            //清空 dataSet ­
            dataSet.Tables["yuanGong"].Clear(); ­
            //实例化 dataAdapter ­
            dataAdapter = new SqlDataAdapter(sql,DBManager.con); ­
            //填充 dataSet ­
            dataAdapter.Fill(dataSet, "yuanGong"); ­
            //将数据绑定到 dataGridView中 ­
            dataGridView1.DataSource = dataSet.Tables["yuanGong"]; ­
/// <summary> ­
/// 更新 数据到数据源 ­
/// </summary> ­
            // 确认修改 ­
            DialogResult result = MessageBox.Show("冯磊老大确定要保存修改吗？", "操作提示",MessageBoxButtons.OKCancel, MessageBoxIcon.Question); ­
            if (result == DialogResult.OK) ­
                { ­
                    // 自动生成更新数据用的命令 ­
                    SqlCommandBuilder comBui = new SqlCommandBuilder(dataAdapter); ­
                    // 将修改过的数据提交到数据库 ­
                    dataAdapter.Update(dataSet, "yuanGong"); ­
                } ­
            //清空 dataSet ­
            dataSet.Tables["yuanGong"].Clear(); ­
            //重新加载数据到 dataGridView 中 ­
            fillDataGridView(); ­
///窗体间传值 ­
   ­
/*公共类*/   ­
   //创建类 ­
   public class readEmail ­
    { ­
      public static string userName=""; ­
      public static string emailName = ""; ­
      public static string emailContent = ""; ­
     ­
    } ­
     ­
/*from1*/ ­
   //将鼠标点击的 listView 行的数据存入 read 类中的变量中 ­
            readEmail.userName  = listView1.SelectedItems[0].SubItems[0].Text.ToString(); ­
            readEmail.emailName = listView1.SelectedItems[0].SubItems[1].Text.ToString(); ­
            readEmail.emailContent  = listView1.SelectedItems[0].SubItems[2].Text.ToString(); ­
   //打开新窗体 ­
            emailWinFrom emailwinfrom = new emailWinFrom(); ­
            emailwinfrom.ShowDialog();   ­
             ­
             ­
/*from2*/ ­
            //将内容显示在新窗体的textbox 中 ­
            textBox2.Text = readEmail.userName; ­
            textBox3.Text = readEmail.emailName; ­
            textBox1.Text = readEmail.emailContent;­