C#增删改查

增删改 语句：

 SqlConnection conn = new SqlConnection("server=.;database=mydb;uid=sa;pwd=123");
 conn.Open();
 //SqlCommand cmd = new SqlCommand(); //构造命令对象
 //cmd.Connection = conn;
 SqlCommand cmd = conn.CreateCommand();
 cmd.CommandText = "insert into info values('p005','田泽','0','n004','1990-6-1')";
 cmd.ExecuteNonQuery();
 conn.Close();
 Console.WriteLine("OK");

查询  语句

SqlConnection conn = new SqlConnection("server=.;database=mydb;uid=sa;pwd=123");//连接类
            conn.Open();
            SqlCommand cmd = conn.CreateCommand();
            cmd.CommandText = "select * from info";
            SqlDataReader dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                Console.WriteLine(dr[0].ToString()+dr[1].ToString()+dr[2].ToString()+dr[3].ToString()+dr[4].ToString());
            }
            conn.Close();

用户密码登录 

Console.Write("账号：");
            string uid = Console.ReadLine();
            Console.Write("密码：");
            string pwd = Console.ReadLine();
            SqlConnection conn = new SqlConnection("server=.;database=mydb;uid=sa;pwd=123");
            conn.Open();
            SqlCommand cmd = conn.CreateCommand();
            cmd.CommandText = "select * from login where username='"+uid+"'and password='"+pwd+"'";
            SqlDataReader dr = cmd.ExecuteReader();
            if (dr.HasRows==false)
            {
                Console.WriteLine("输入的用户密码不正确 请重新输入");            
            }
            else
            {
                Console.WriteLine ("登录成功");
            }
            conn.Close();