//增加、删除、更新、查询公用       

string MyConn = "server=127.0.0.1;uid=数据库登录名;pwd=密码;database=数据库的名字;Trusted_Connection=no";
SqlConnection MyConnection = new SqlConnection(MyConn);

          string MyInsert = "想要执行的sql语句";
          SqlCommand MyCommand = new SqlCommand(MyInsert, MyConnection);
          MyConnection.Open();
          MyCommand.ExecuteNonQuery();
          MyConnection.Close();

2、删除

           string MyDelete = "想要执行的sql语句";
            SqlCommand MyCommand = new SqlCommand(MyDelete, MyConnection);
            MyConnection.Open();
            MyCommand.ExecuteNonQuery();
            MyConnection.Close();

3、更新

           string MyUpdate = "想要执行的sql语句";
            SqlCommand MyCommand = new SqlCommand(MyUpdate, MyConnection);
            MyConnection.Open();
            MyCommand.ExecuteNonQuery();
             MyConnection.Close();

4、查询

            MyConn.Open();
            SqlDataAdapter dap = new SqlDataAdapter("想要执行的sql语句",MyConn);
            DataSet ds = new DataSet();//实例化DataSet类
            dap.Fill(ds, "Table");//添加SQL语句并执行
            dataGridView1.DataSource = ds.Tables[0].DefaultView;//显示数据