ConnectionString 属性尚未初始化。 找错

Question

  OleDbConnection connection = new OleDbConnection(ConfigurationManager.AppSettings["sql"]);
        string sql = "select * from [SalesInfo]";
        OleDbDataAdapter da = new OleDbDataAdapter(sql, connection);
        DataSet ds = new DataSet();
        da.Fill(ds);
<appSettings>
<add key="sql " value="Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\SalesProjects\App_Data\1.accdb;Persist Security Info=True "/>
</appSettings>
哪里出错了  没搞错access数据库- -

Answer 1

还没有open
就是connection。open();

Answer 2

换成在 <connectionStrings>.......</connectionStrings>节点中试试