ADO.NET三个经典案例

程序要和数据库交互要通过ADO.NET进行，通过AOD.NET就能在程序中执行SQL了

项目内嵌mdf文件形式的连接字符串  必须加
            string dataDir = AppDomain.CurrentDomain.BaseDirectory;
            if (dataDir.EndsWith(@"\bin\Debug\")
                || dataDir.EndsWith(@"\bin\Release\"))
            {
                dataDir = System.IO.Directory.GetParent(dataDir).Parent.Parent.FullName;
                AppDomain.CurrentDomain.SetData("DataDirectory", dataDir);
            }


ADO.NET经典案例
例1：插入数据：
using (SqlConnection conn = new SqlConnection(@"Data Source=(LocalDB)\v11.0;AttachDbFilename=E:\C#程序\第二阶段\第二阶段\ADO.NET入门\AOD.net.mdf;Integrated Security=True"))
            {
                conn.Open();
                    using(SqlCommand cmd=conn.CreateCommand())
                    {
                        cmd.CommandText="insert into fuser(username,passwors)values('admin','888');";
                        cmd.ExecuteNonQuery();
                        Console.WriteLine("插入成功");
                    }

            }
            Console.WriteLine("测试正常");
            Console.ReadKey();


列2：登录验证：
Console.WriteLine("输入用户名");
            string username= Console.ReadLine();
            Console.WriteLine("输入密码");
            string password= Console.ReadLine();
            using (SqlConnection coon = new SqlConnection(@"Data Source=(LocalDB)\v11.0;AttachDbFilename=E:\C#程序\第二阶段\第二阶段\ADO.NET入门\AOD.net.mdf;Integrated Security=True"))
            {
                coon.Open();
                using(SqlCommand cmd=coon.CreateCommand())//创建与数据库交谈的命令
                {
                    cmd.CommandText = "select *from fuser where username='"+username+"'";//先到表中查用户输入的用户名对应的信息
                    using( SqlDataReader reader=cmd.ExecuteReader())
                    {
                        if (reader.Read())
                        {
                            //用户名存在
                            string dbpass = reader.GetString(reader.GetOrdinal("passwors"));//比较数据库中记录的密码和用户输入的密码是否一致
                            if (password == dbpass)
                            {
                                Console.WriteLine("登录成功");
                            }
                            else { Console.WriteLine("密码错误"); }

                        }
                        else
                        {
                            Console.WriteLine("用户名错误");
                        }
                    }

                }
            }

            Console.WriteLine("测试正常");
            Console.ReadKey();

例3登录验证参数化查询：防止注入漏洞：
            连接数据库onsole.WriteLine("请输入用户名");
            string username = Console.ReadLine();
            Console.WriteLine("请输入密码");
            string password = Console.ReadLine();
            using (SqlConnection coon = new SqlConnection(@"Data Source=(LocalDB)\v11.0;AttachDbFilename=E:\C#程序\第二阶段\第二阶段\ADO.NET入门\AOD.net.mdf;Integrated Security=True"))
            {
                coon.Open();
                using (SqlCommand cmd = coon.CreateCommand())
                {
                    cmd.CommandText = "select count(*) from fuser where username='" + username + "' and  passwors='" + password + "'";
                    cmd.CommandText = "select count(*) from fuser where username=@zh and passwors=@mm";
                    cmd.Parameters.Add(new SqlParameter("@zh",username));
                    cmd.Parameters.Add(new SqlParameter("@mm",password));
                    int i = Convert.ToInt32(cmd.ExecuteScalar());
                    if (i > 0)
                    {
                        Console.WriteLine("登录成功");
                    }
                    else
               {
                        Console.WriteLine("用户名或密码错误");
                    }
                }
                
            }
            */
            Console.WriteLine("测试成功");
            Console.ReadKey();