未将对象引用设置到对象的实例

Question

web.config中
<connectionStrings>
  <add name="ConnectionString" connectionString="Data Source=(local);Initial Catalog=gsq;User ID=sa;Password=sa" providerName="System.Data.SqlClient" />
 </connectionStrings>
网页中
  public SqlConnection GetConnection()
    {
          
     
       String mystr = ConfigurationManager.AppSettings["ConnectionString"].ToString();
        SqlConnection myconn = new SqlConnection(mystr);
        return myconn;
    } String mystr = ConfigurationManager.AppSettings["ConnectionString"].ToString();报错急求高手解决~小弟在此谢过

Answer 1

string connStr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

Answer 2

ConfigurationManager.ConnectionString["connectionString"].ConnectionString;

Answer 3

请用ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

Answer 4

请问ConnectionString是自带函数，还是add name="ConnectionString" connectionString中我自己定义的？
新手，谢谢指教~

Answer 5

修改后继续报错
错误 2 “string”并不包含“ConnectionString”的定义 e:\inetpub\wwwroot\myweb\addproduct.aspx.cs 29 77 e:\...\myweb\

Answer 6

string connStr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
已经改过来，但还是有
标题的错误警告

Answer 7

string connStr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString; 

Answer 8

String mystr = ConfigurationManager.AppSettings["ConnectionString"]不要加TOSTRING()