C# 學習筆記之增刪改查操作

因爲之前有個CSDN的賬號但是後來賬號丟了，於是只能另起爐竈，今天總有找回了丟失已久的登錄祕密，不知道有沒有辦法將兩個博客合併，只能手動複製黏貼以前的博文過來。。。悲慘
源地址：http://blog.csdn.net/sxfenglei/article/details/5431264 該博客不再用了
現在看看當年寫的代碼真幼稚呵呵轉過來紀念下當年的稚嫩，哈哈
/// <summary> 
/// 對話框返回值 
/// 
///這是一個退出按鍵的方法，用來確定用戶是否真的要退出 
/// </summary> 
        private void 退出ToolStripMenuItem_Click(object sender, EventArgs e) 
        { 
            //定義 DialogResult 變量 用以存儲對話框返回值 
            DialogResult exitForm; 
            //對話框 
            exitForm = MessageBox.Show("馮磊老大您確定要離開我嗎？","退出系統",MessageBoxButtons.OKCancel,MessageBoxIcon.Information); 
            //判斷 
            if (exitForm == DialogResult.OK)   //使用 DialogResult 屬性判斷該按鈕的返回值是否爲 "確定" 
            { 
                Application.Exit();//退出系統 
            } 
        } 
/// <summary> 
/// 創建 DBManager 類 
/// 
/// 在 DBManager 類中創建數據庫連接 
/// </summary> 
  class DBManager 
   { 
    //連接數據庫字符串 和 實例化 connection 對象 
    private static string sqlconString = "Data Source=ASUS//SQLEXPRESS;Initial Catalog=MyDB;Integrated Security=True"; 
    public static SqlConnection con = new SqlConnection(sqlconString); 
   } 
/// <summary> 
/// 創建 User 類 
/// 
/// 在 User 類中創建 用於存儲交換的變量 
/// </summary> 
  class User 
   { 
    public string userID = ""; 
    public string userName = ""; 
    public string userAge = ""; 
    public string userGongZi = ""; 
    public string userJiGuan = ""; 
   } 
/// <summary> 
        /// ExecuteScalar()方法 返回單個值 
         
        /// 核心 SELECT COUNT(*) FROM Student 
        /// 核心 com.ExecuteScalar(); 
/// </summary> 
//定義數據庫連接字符串 和 connection 對象 
string sqlString = "Data Source=ASUS//SQLEXPRESS;Initial Catalog=MySchool;Integrated Security=True"; 
SqlConnection con = new SqlConnection(sqlString); 
//打開數據庫 
con.Open(); 
//拼SQL語句 和 創建 command 對象 
string sql = "SELECT COUNT(*) FROM Student "; 
SqlCommand com = new SqlCommand(sql,con); 
// 執行 SQL 查詢 使用ExecuteScaler()方法 返回一個讀取值 
int num = (int)com.ExecuteScalar(); 
//將返回值格式化後存入變量中 後輸出 
string message = string.Format("Student表中共有{0}條學員信息！", num); 
MessageBox.Show(message, "查詢結果", MessageBoxButtons.OK, MessageBoxIcon.Information);//然後將該變量輸出 
//關閉數據庫 
con.Close(); 
/// <summary> 
        ///  將數據加載到 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> 
            //定義數據庫字符 和 connection 對象 
            string sqlString = "Data Source=ASUS//SQLEXPRESS;Initial Catalog=MySchool;Integrated Security=True"; 
            SqlConnection con = new SqlConnection(sqlString); 
            //定義sql語句 和 command 對象 
            string sql = "select studentName from student"; 
            SqlCommand com = new SqlCommand(sql, con); 
            //打開數據庫 
            con.Open(); 
            //執行sql讀取 使用dataReader對象 
            SqlDataReader dataReader = com.ExecuteReader(); 
            //循環讀取每一條數據 添加到comboBox1 中 
            string studentName = "";//將每條讀取存入這個變量 用以每次想comboBox1中添加 
            while (dataReader.Read()) 
            { 
                studentName = (string)dataReader[0];//從第0項開始讀取 
                comboBox1.Items.Add(studentName);//添加每條讀取到 comboBox1 中 
            } 
            //關閉讀取 和 數據庫 
            dataReader.Close(); 
            con.Close(); 
/// <summary> 
        /// 將數據加載到 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(); 
            //定義數據庫字符 和 connection 對象 
            string sqlconString = "Data Source=ASUS//SQLEXPRESS;Initial Catalog=MySchool;Integrated Security=True"; 
            SqlConnection con = new SqlConnection(sqlconString);//上面定義過 
            //拼SQL 和 command 對象 
            string sql = "select * from admin";//上面定義過 
            SqlCommand com = new SqlCommand(sql, con);//上面定義過 
            con.Open(); 
            //執行SQL語句 
            SqlDataReader dataReader = com.ExecuteReader(); 
            //定義存儲變量 
            string id = ""; 
            string adminUser = ""; 
            string adminPwd = ""; 
            //循環讀取數據庫 數據 然後存入變量中 
            while (dataReader.Read()) 
            { 
                //將數據庫中的數據讀取到變量中 
                id = dataReader["adminId"].ToString();//拿到ID 
                adminUser = dataReader["LoginId"].ToString(); 
                adminPwd = dataReader["LoginPwd"].ToString(); 
                //創建 ListView 項 
                ListViewItem liv = new ListViewItem(adminUser);//將 adminUser 加載到第一項中 
                liv.Tag = (int)dataReader["adminId"]; 
                listView1.Items.Add(liv);//向listView1中添加一個新項 
                liv.SubItems.AddRange(new string[] { adminPwd });//將剩餘項 adminPwd 添加到listView1中 
            } 
            dataReader.Close(); 
            con.Close(); 
        }     
/// <summary> 
  /// 單擊 listView 時 將本行數據存入 user 類中的變量中 
        /// 核心 定義 user 類 
        /// 核心 使用 listView1.SelectedItems[0].SubItems[1].Text.ToString(); 拿到數據 並存入user 類中(需要實例化) 
/// </summary> 
        private void listView1_Click(object sender, EventArgs e) 
        { 
            //實例化 User 類 
            User us = new User(); 
            //將鼠標點擊的 listView 行的數據存入 user 類中的變量中 
            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(); 
            //將 user類中的數據在放到 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> 
   //判斷非空 
            if(textBox1.Text.Trim()=="") 
            { 
                MessageBox.Show("馮磊老大你叫啥？"); 
                textBox1.Focus();//得到焦點 
                return;//如果爲空則返回空 即結束 
            }else if(textBox2.Text.Trim()=="") 
            { 
                MessageBox.Show("馮磊老大告訴我密碼？"); 
                textBox2.Focus(); 
                return; 
            } 
            //定義數據庫連接 和 connection 對象 
            string sqlconString = "Data Source=ASUS//SQLEXPRESS;Initial Catalog=MySchool;Integrated Security=True"; 
            SqlConnection con = new SqlConnection(sqlconString ); 
            //拼SQL 和 command 對象 
            string sql = string.Format("insert into admin (LoginId,LoginPwd) values ('{0}','{1}')",textBox1.Text,textBox2.Text); 
            SqlCommand com = new SqlCommand(sql,con ); 
            con.Open(); 
            //添加數據到數據庫 使用ExecutenNonQuery方法 
            int num =com.ExecuteNonQuery(); 
            //如果添加成功側提示 
            if (num==1) 
            { 
                MessageBox.Show("馮磊老大添加成功！"); 
            } 
            else { 
                MessageBox.Show("哦哦~~馮磊老大添加失敗！","",MessageBoxButtons.OK,MessageBoxIcon.Error); 
            } 
            con.Close(); 
   //在加載 一遍 listView 可以將創建的listView 抽成方法 如 fillListView(); 
   fillListView(); 
/// <summary> 
        ///  刪 
         
        /// 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> 
   //確保用戶選擇了一個學員才執行修改操作 
            if(listView1.SelectedItems.Count==0) 
            { 
                MessageBox.Show("馮磊老大你不告訴我刪除那個我怎麼刪"); 
                return; 
            }else{ 
                 
                //定義數據庫連接字符串 和 connection 對象 
                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(); 
                //執行SQL 
                 int test = com.ExecuteNonQuery(); 
                //提示刪除成功與否 
                 if (test > 0) 
                 { 
                     MessageBox.Show("馮磊老大我成功的給你滅了它！"); 
                 } 
                 else { 
                     MessageBox.Show("馮磊老大我滅它失敗！"); 
                 } 
                con.Close(); 
            } 
            /* listView */ 
            FillListView();//加載FillListView(); 
/// <summary> 
  /// 右鍵 刪除 
   
  /// 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();//加載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("馮磊老大修改失敗！", "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~~~馮磊老大沒有在國防部查到你要的數據!"); 
    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);  //拿到第一列的單元格的值 
//============================================================================================
/// <summary> 
/// 創建 全局變量 
/// </summary> 
        //實例化 dataSet 和 聲明 dataAdapter 
        DataSet dataSet = new DataSet(); 
        SqlDataAdapter dataAdapter; 
        //聲明字符 
        string sql =""; 
         
         
         
         
/// <summary> 
/// 創建 fillDataGridView方法 
/// </summary> 
        private void fillDataGridView() 
        { 
            //拼基本 SQL 語句 
            sql = "select id as 編號,name as 姓名,age as 年齡,gongzi as 工資,jiguan as 籍貫 from yuangong "; 
            //實例化 dataAdapter 
            dataAdapter = new SqlDataAdapter(sql, DBManager.con); 
            //填充 dataSet 
            dataAdapter.Fill(dataSet, "yuanGong"); 
            //將數據綁定到 dataGridView中 
            dataGridView1.DataSource = dataSet.Tables["yuanGong"]; 
        } 
         
         
         
         
/// <summary> 
/// 篩選 數據 
/// </summary> 
            //刷新基本 SQL 語句 
            sql = "select id as 編號,name as 姓名,age as 年齡,gongzi as 工資,jiguan as 籍貫 from yuanGong "; 
            //拼接 條件SQL 語句 
            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 "陝西": 
                    sql = sql + "where jiguan='陝西'"; 
                    break; 
                case "河北": 
                    sql = sql + "where jiguan='河北'"; 
                    break; 
                case "青島": 
                    sql = sql + "where jiguan='青島'"; 
                    break; 
            } 
            //清空 dataSet 
            dataSet.Tables["yuanGong"].Clear(); 
            //實例化 dataAdapter 
            dataAdapter = new SqlDataAdapter(sql,DBManager.con); 
            //填充 dataSet 
            dataAdapter.Fill(dataSet, "yuanGong"); 
            //將數據綁定到 dataGridView中 
            dataGridView1.DataSource = dataSet.Tables["yuanGong"]; 
/// <summary> 
/// 更新 數據到數據源 
/// </summary> 
            // 確認修改 
            DialogResult result = MessageBox.Show("馮磊老大確定要保存修改嗎？", "操作提示",MessageBoxButtons.OKCancel, MessageBoxIcon.Question); 
            if (result == DialogResult.OK) 
                { 
                    // 自動生成更新數據用的命令 
                    SqlCommandBuilder comBui = new SqlCommandBuilder(dataAdapter); 
                    // 將修改過的數據提交到數據庫 
                    dataAdapter.Update(dataSet, "yuanGong"); 
                } 
            //清空 dataSet 
            dataSet.Tables["yuanGong"].Clear(); 
            //重新加載數據到 dataGridView 中 
            fillDataGridView(); 
///窗體間傳值 
   
/*公共類*/   
   //創建類 
   public class readEmail 
    { 
      public static string userName=""; 
      public static string emailName = ""; 
      public static string emailContent = ""; 
     
    } 
     
/*from1*/ 
   //將鼠標點擊的 listView 行的數據存入 read 類中的變量中 
            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(); 
   //打開新窗體 
            emailWinFrom emailwinfrom = new emailWinFrom(); 
            emailwinfrom.ShowDialog();   
             
             
/*from2*/ 
            //將內容顯示在新窗體的textbox 中 
            textBox2.Text = readEmail.userName; 
            textBox3.Text = readEmail.emailName; 
            textBox1.Text = readEmail.emailContent;
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