ADO.NET 用windows方式连接数据库以及简单的增，删，改，查询操作

static void Main(string[] args)
        {
            //Program p = new Program();
            //p.Open();
            //Open1();
            //AddRecord();
            QuerySingle();

        }
        public static string conStr = @"server=.\SQLEXPRESS;database=mydb2;Integrated Security=True;";

        #region 1.成员方式打开数据库
        /// <summary>
        /// 成员方式
        /// </summary>
        public void Open()
        {
            string connstr = @"server=.\SQLEXPRESS;database=mydb2;Integrated Security=True";
            SqlConnection conn = new SqlConnection();//创建数据库连接
            conn.ConnectionString = connstr;
            conn.Open();//打开数据库
            Console.WriteLine("打开成功");
            conn.Close();//关掉数据库 
        }
        
        #endregion

        #region 2.静态方法，直接调用就可以
        /// <summary>
        /// 静态方法，直接调用就可以
        /// </summary>
        public static void Open1()
        {
            string connstr = @"server=.\SQLEXPRESS;database=mydb2;Integrated Security=True";
            SqlConnection conn = new SqlConnection(connstr);
            conn.Open();
            conn.Close();
            Console.WriteLine("1111");
      

        } 
        #endregion

        #region 3.增加。删除，修改

        /// <summary>
        /// 增加，删除，修改都是用sqlCommand的ExecuteNonQuery
        /// </summary>
        public static void AddRecord()
        {
            SqlConnection conn = new SqlConnection(conStr);
            conn.Open();
            string cmdStr = "insert into category(C_Name,C_Remark)values('英语','这也太难了吧')";
            SqlCommand cmd = new SqlCommand(cmdStr, conn);
            int res = -1;//看影响的行数有多少
            res = cmd.ExecuteNonQuery();
            if (res > 0)
            {
                Console.WriteLine("增加成功");
            }
            else Console.WriteLine("增加失败");
            conn.Close();//关掉数据库 

        } 
        #endregion

        #region 4.查询并返回记录中的第一行，第一列的值

        /// <summary>
        /// 查询，并返回结果集中的第一行，第一列
        /// </summary>
        public static void QuerySingle()
        {
            SqlConnection conn = new SqlConnection(conStr);
            conn.Open();
            string cmdStr = "select * from category";
            SqlCommand cmd = new SqlCommand(cmdStr, conn);

            object obj = cmd.ExecuteScalar();
            Console.WriteLine(obj);
            conn.Close();//关掉数据库 

        } 
        #endregion