我的数据库连接哪有错呢？
WEBCONFIG里的连接字符串
<connectionStrings>
<add   name= "abc "   connectionString= "Data   Source=HINJX3COJZB09GL;Initial   Catalog=duke;Integrated   Security=True "   providerName= "System.Data.SqlClient "/>
</connectionStrings>

后台连接：
SqlConnection   conn   =   new   SqlConnection(ConfigurationManager.AppSettings[ "abc "]);
conn.Open();
SqlCommand   cmd   =   new   SqlCommand( "SELECT   *   FROM   duke ",   conn);
SqlDataAdapter   da   =   new   SqlDataAdapter(cmd);
DataSet   ds   =   new   DataSet();
da.Fill(ds);
conn.Close();

提示是：   conn.Open(）未初始化.   请问是不是因为数据库没连接通？


------解决方案--------------------
ConfigurationManager.AppSettings[ "abc "]);
这个是读AppSettings中的设置。而你是放在connectionStrings下了，而且写法也不对。
------解决方案--------------------
ConfigurationManager.ConnectionStrings
------解决方案--------------------
<appSettings>
<add key= "ConnectionString " value= "server=.;database=Test;uid=sa;pwd=; "> </add>
</appSettings>

string conn= System.Configuration.ConfigurationSettings.AppSettings[ "ConnectionString "];
conn.Open();
SqlCommand cmd = new SqlCommand( "SELECT * FROM duke ", conn);
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
conn.Close();