在web.config 中输入 ConnectionString 避免每次连接数据库都要写 ConnectionString

web.config

<configuration>

<appSettings>
  <add key="DBConnectionString" value="server=localhost;database=web;uid=sa; pwd="/>
 </appSettings>
</configuration>

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xxx.aspx.cs

SqlConnection conn = new SqlConnection(ConfigurationManager.AppSettings["DBConnectionString"]);