为什么下面这句会出错?错哪 了?
string conn = HttpContext.Current.Server.MapPath("tushuguan.mbd");
总是提示:
未处理的“System.NullReferenceException”类型的异常出现在 tushuguanli.exe 中。其他信息: 未将对象引用设置到对象的实例。代码如下:
//连接数据库
string conn = HttpContext.Current.Server.MapPath("tushuguan.mbd");
string connectionString ="Provider=Microsoft.Jet.OLEDB.4.0; DataSource= " + conn;//创建command对象并保存sql查询语句
OleDbConnection myOleDbConnection = new OleDbConnection(connectionString);
OleDbCommand myOleDbCommand = myOleDbConnection.CreateCommand();
myOleDbCommand.CommandText ="SELECT ID, pwd "+"FROM login ";
myOleDbConnection.Open();
........
string conn = HttpContext.Current.Server.MapPath("tushuguan.mbd");
总是提示:
未处理的“System.NullReferenceException”类型的异常出现在 tushuguanli.exe 中。其他信息: 未将对象引用设置到对象的实例。代码如下:
//连接数据库
string conn = HttpContext.Current.Server.MapPath("tushuguan.mbd");
string connectionString ="Provider=Microsoft.Jet.OLEDB.4.0; DataSource= " + conn;//创建command对象并保存sql查询语句
OleDbConnection myOleDbConnection = new OleDbConnection(connectionString);
OleDbCommand myOleDbCommand = myOleDbConnection.CreateCommand();
myOleDbCommand.CommandText ="SELECT ID, pwd "+"FROM login ";
myOleDbConnection.Open();
........
*****************************************************************************
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http://www.cnblogs.com/feiyun0112/archive/2006/09/20/509783.html