C#中怎么把sql数据库的一个数据赋值给一个变量

连接数据库,并从数据库中读取数据后并输出!

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
namespace Login
{
    class Program
    {
        static void Main(string[] args)
        {
            //新建一个数据库连接
            using(SqlConnection conn = new SqlConnection(GetConnectString()))
            {
                conn.Open();//打开数据库
                //Console.WriteLine("数据库打开成功!");
                //创建数据库命令
                SqlCommand cmd = conn.CreateCommand();
                //创建查询语句
                cmd.CommandText = "SELECT * FROM userinfo";
                //从数据库中读取数据流存入reader中
                SqlDataReader reader = cmd.ExecuteReader();               
                
                //从reader中读取下一行数据,如果没有数据,reader.Read()返回flase
                while (reader.Read())
                {
                    //reader.GetOrdinal("id")是得到ID所在列的index,
                    //reader.GetInt32(int n)这是将第n列的数据以Int32的格式返回
                    //reader.GetString(int n)这是将第n列的数据以string 格式返回
                    int id = reader.GetInt32(reader.GetOrdinal("id"));
                    string name = reader.GetString(reader.GetOrdinal("name"));
                    string pwd = reader.GetString(reader.GetOrdinal("password"));
                    int age = reader.GetInt32(reader.GetOrdinal("age"));
                    string sex = reader.GetString(reader.GetOrdinal("sex"));
                    string phone = reader.GetString(reader.GetOrdinal("phone"));
                    string address = reader.GetString(reader.GetOrdinal("Address"));
                    //格式输出数据
                    Console.Write("ID:{0},Name:{1},PWD:{2},Age:{3},Sex:{4},Phone{5},Address:{6}\n", id, name, pwd, age, sex, phone, address);
                }
            }
            Console.ReadKey();
        }
        //得到一个数据库连接字符串
        static string GetConnectString()
        {
            return "Data Source=(local);Initial Catalog=db1;Integrated Security=SSPI;";
        }
    }
}