配置方式：
App.config文件中按格式配置
<configuration>

　　<connectionStrings>
　　　　<add name="MyDbConnectionString"
　　　　connectionString="Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;"
　　　　providerName="System.Data.SqlClient"/>
　　　　</connectionStrings>
</configuration>

按格式配置例子
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <configSections>
    </configSections>
    <connectionStrings>
        <add name="Cn.ZhongYi.Properties.Settings.zhongyiConnectionString"
            connectionString="Data Source=CCNN13\CCNN13;Initial Catalog=zhong;User ID=sa;Password=myPassword"
            providerName="System.Data.SqlClient" />
    </connectionStrings>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.7.2" />
    </startup>
</configuration>