Asp.net ConfigurationManager无法识别我的连接字符串

我正在尝试使用ASP.Net Web表单从数据库中执行一个

下拉列表

页面加载：

        protected void Page_Load(object sender, EventArgs e)
        {
            OracleConnection conn = new OracleConnection();
            conn.ConnectionString = ConfigurationManager.ConnectionStrings["OraDbContext"].ConnectionString;
            OracleCommand cmd = new OracleCommand("SELECT NOMPRE FROM HOPEMPL", conn); //HOPEMPL@HQ
            OracleDataAdapter oda = new OracleDataAdapter(cmd);
            DataSet ds = new DataSet();
            oda.Fill(ds);
            DDnompre.DataSource = ds;
            DDnompre.DataTextField = "NOMPRE";
            DDnompre.DataValueField = "NOMPRE";
            DDnompre.DataBind();

        }

  <connectionStrings>
    <add name="OraDbContext" connectionString="metadata=res://*/Models.Model1.csdl|res://*/Models.Model1.ssdl|res://*/Models.Model1.msl;provider=Oracle.ManagedDataAccess.Client;provider connection string=&quot;DATA SOURCE=localhost:1521/xe;DBA PRIVILEGE=;PASSWORD=1234;USER ID=LOUG&quot;" providerName="System.Data.EntityClient" />
  </connectionStrings>

连接字符串：

        protected void Page_Load(object sender, EventArgs e)
        {
            OracleConnection conn = new OracleConnection();
            conn.ConnectionString = ConfigurationManager.ConnectionStrings["OraDbContext"].ConnectionString;
            OracleCommand cmd = new OracleCommand("SELECT NOMPRE FROM HOPEMPL", conn); //HOPEMPL@HQ
            OracleDataAdapter oda = new OracleDataAdapter(cmd);
            DataSet ds = new DataSet();
            oda.Fill(ds);
            DDnompre.DataSource = ds;
            DDnompre.DataTextField = "NOMPRE";
            DDnompre.DataValueField = "NOMPRE";
            DDnompre.DataBind();

        }

  <connectionStrings>
    <add name="OraDbContext" connectionString="metadata=res://*/Models.Model1.csdl|res://*/Models.Model1.ssdl|res://*/Models.Model1.msl;provider=Oracle.ManagedDataAccess.Client;provider connection string=&quot;DATA SOURCE=localhost:1521/xe;DBA PRIVILEGE=;PASSWORD=1234;USER ID=LOUG&quot;" providerName="System.Data.EntityClient" />
  </connectionStrings>



错误：

        protected void Page_Load(object sender, EventArgs e)
        {
            OracleConnection conn = new OracleConnection();
            conn.ConnectionString = ConfigurationManager.ConnectionStrings["OraDbContext"].ConnectionString;
            OracleCommand cmd = new OracleCommand("SELECT NOMPRE FROM HOPEMPL", conn); //HOPEMPL@HQ
            OracleDataAdapter oda = new OracleDataAdapter(cmd);
            DataSet ds = new DataSet();
            oda.Fill(ds);
            DDnompre.DataSource = ds;
            DDnompre.DataTextField = "NOMPRE";
            DDnompre.DataValueField = "NOMPRE";
            DDnompre.DataBind();

        }

  <connectionStrings>
    <add name="OraDbContext" connectionString="metadata=res://*/Models.Model1.csdl|res://*/Models.Model1.ssdl|res://*/Models.Model1.msl;provider=Oracle.ManagedDataAccess.Client;provider connection string=&quot;DATA SOURCE=localhost:1521/xe;DBA PRIVILEGE=;PASSWORD=1234;USER ID=LOUG&quot;" providerName="System.Data.EntityClient" />
  </connectionStrings>

System.ArgumentException:“元数据”不是有效的连接
字符串属性“”

我还在使用数据库优先（EF）
尝试：

 <add name="{ConnectionName}" 
        connectionString="Data Source=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=MyHost)(PORT=MyPort)))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=MyOracleSID)));User Id=myUsername;Password=myPassword;" 
        providerName="Oracle.DataAccess.Client"/>

它工作了，但我现在无法访问数据库，它显示无效的用户名或密码，我没有弄错它们。。。