sql server数据库连接字符串

App.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <connectionStrings>
    <add name="sqlconn" connectionString="Data Source=7806221B71404F3\SQLEXPRESS;Initial Catalog=mydb; User ID=sa;Pwd=123"/>
  </connectionStrings>
</configuration>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
using System.Configuration;

namespace ADO
{
    class Program
    {
        static void Main(string[] args)
        {
string connStr = ConfigurationManager.ConnectionStrings["sqlconn"].ConnectionString;
            //string connStr = @"Data Source=7806221B71404F3\SQLEXPRESS;Initial Catalog=mydb; User ID=sa;Pwd=123";
            SqlConnection conn = new SqlConnection(connStr);
            conn.Open();
            SqlCommand cmd = conn.CreateCommand();
            //cmd.CommandText = "select count(*) from emp";
            //int i = (int)cmd.ExecuteScalar();
            //Console.WriteLine(i.ToString());
            SqlDataReaderTest(cmd);
            conn.Dispose();
            Console.ReadKey();
        }

        private static void SqlDataReaderTest(SqlCommand cmd)
        {
            cmd.CommandText = "select * from emp";
            SqlDataReader dr = cmd.ExecuteReader();
            if (dr.HasRows)
            {
                while (dr.Read())
                { 
                    string ename = dr["ename"].ToString();
                    int empno = Convert.ToInt32(dr["empno"]);
                    double sal = Convert.ToDouble(dr["sal"]);
                    Console.WriteLine(ename + " " + sal);
                }
            }
            dr.Close();
        }
    }
}