关于一个cast的问题
代码片段如下: 
 			double[,]   sale   =   new   double[dt1.Rows.Count,1]; 
 			OleDbCommand   com5   =   new   OleDbCommand( "SELECT   Sale   FROM   E_Store ",   conn); 
 			OleDbDataReader   dr2   =   com5.ExecuteReader(); 
 			while(dr2.Read()) 
 			{ 
 				sale[dr2.Depth,0]   =   (double)dr2.GetValue(0); 
 			} 
 			dr2.Close();   
 问题出在cast那行。。。。。。   
 sale的数据全是double的值   
 请问问题在那?、   
 谢谢 
------解决方案--------------------Convert.ToDouble(dr2.GetValue(0));
------解决方案--------------------double[,] sale = new double[dt1.Rows.Count,1]; 
 OleDbCommand com5 = new OleDbCommand( "SELECT Sale FROM E_Store ", conn); 
 OleDbDataReader dr2 = com5.ExecuteReader(); 
 while(dr2.Read()) 
 { 
 	sale[dr2.Depth,0] = dr2.GetDouble(0); 
 } 
 dr2.Close();