<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <connectionStrings>
    <add name="zxz" connectionString="Data Source=192.168.1.81;Database=SMRS;User id=sa;PWD=reasee#1206"
providerName="System.Data.SqlClient" />
  </connectionStrings>
  <appSettings>
    <add key="ConnectionString" value="Server=192.168.1.81;user id=sa;password=reasee#1206;database=SMRS"/>
  </appSettings>
</configuration>

在方案里添加：1）添加引用System.Configuration

2）在.CS文件头上加上 using System.Configuration;

 项目中调用：如果是connectionStrings，用ConfigurationManager.ConnectionStrings["add的name"].ConnectionString;

如果是appSettings，用ConfigurationManager.AppSettings["add的key"].ToString();
如：public static string SqlConnString = ConfigurationManager.AppSettings["ConnectionString"].ToString();