请教:ConnectionString 属性尚未初始化?

Question

我在web.config里是这样写的
 <add name="AccessConn" connectionString="Provider=Microsoft.Jet.OleDB.4.0;Data Source=~/App_Data/area.mdb" providerName="System.Data.OleDB"></add>   protected void Page_Load(object sender, EventArgs e)
    {
        string connString = System.Configuration.ConfigurationSettings.AppSettings["AccessConn"];        //string connString = "Provider=Microsoft.Jet.OleDB.4.0;Data Source=" + Server.MapPath("~/App_Data/area.mdb");
        OleDbConnection conn = new OleDbConnection(connString);
        OleDbCommand comm = new OleDbCommand("select area from area", conn);
        conn.Open();
        OleDbDataReader dr = comm.ExecuteReader();
        if (dr.Read())
        {
            Response.Write(dr["area"].ToString());
        }
}
不是写在web.config里是可以 请问一下 应该怎么写?

Answer 1

web.config
....
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
<connectionStrings>
<add name="ConnString" connectionString="\\App_Data\\db.mdb" providerName="System.Data.OleDB"/>
</connectionStrings> static string  strp = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=";
 protected static string connectionString =strp+System.Web.HttpContext.Current.Server.MapPath("~")+ConfigurationManager.ConnectionStrings["ConnString"].ConnectionString;

Answer 2

<configuration>
  <appSettings>
    <add key="AccessConn" value="你的connString"/>

Answer 3

如果是.NET 2.0的，用2楼的可以

Answer 4

但我估计楼主不是2.0的，因为
ConfigurationSettings.AppSettings在2.0中是已过时的属性

Answer 5

web.config  <add name="AccessConn" connectionString="Provider=Microsoft.Jet.OleDB.4.0;Data Source=\\App_Data\\area.mdb" providerName="System.Data.OleDB"></add>---------------
    protected void Page_Load(object sender, EventArgs e)
    {
        string connString = System.Configuration.ConfigurationManager.AppSettings["AccessConn"];
    
        OleDbConnection conn = new OleDbConnection(connString);
        OleDbCommand comm = new OleDbCommand("select area from area", conn);
        conn.Open();
        OleDbDataReader dr = comm.ExecuteReader();        if (dr.Read())
        {
            Response.Write(dr["area"].ToString());
        }
         }我改了 怎么还是不行!

Answer 6

<add name="AccessConn" connectionString="Provider=Microsoft.Jet.OleDB.4.0;Data Source=\\App_Data\\area.mdb" providerName="System.Data.OleDB"></add> string connString = System.Configuration.ConfigurationManager.AppSettings["AccessConn"];-------------------------------------
定义的connectionstring 节点，调用的却是appsettings节点？
<appSettings>
    <add key="AccessConn" value="你的connString"/>
</appSettings>
 string connString = System.Configuration.ConfigurationManager.AppSettings["AccessConn"];

Answer 7

設置：
<?xml version="1.0" encoding="utf-8"?>
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
    <connectionStrings>
        <add name="AccessConn" connectionString="Provider=Microsoft.Jet.OleDB.4.0;Data Source=~/App_Data/area.mdb" providerName="System.Data.OleDB"></add>
    </connectionStrings>
    <system.web>
        
    </system.web>
</configuration> 讀取：
string strConn=System.Configuration.ConfigurationManager.ConnectionStrings[0].ConnectionString;

Answer 8

不好意思，還是
 string connString = System.Configuration.ConfigurationManager.AppSettings["AccessConn"];好些，System.Configuration.ConfigurationManager.ConnectionStrings[0].ConnectionString;不一定就是上面設置的connectionString

Answer 9

Access的连接串建议在Web.Config里只写地址.如果要写整个串,请使用本地硬盘的绝对路径如Provider=Microsoft.Jet.OleDB.4.0;Data Source=C:\WEB\App_Data\area.mdb
而不是
Provider=Microsoft.Jet.OleDB.4.0;Data Source=~/App_Data/area.mdb
建议只写地址
<add name="AccessPath" Value="~/App_Data/area.mdb"></add>
读取时用:
string connString = "Provider=Microsoft.Jet.OleDB.4.0;Data Source=" + Server.MapPath(ConfigurationSettings.AppSettings["AccessPath"]);
另外,你上面的web.config中是2005里的ConnectionString配置节写法, 代码是用2003的读取方法,应该是这里的问题,你用的是05还是03?