Asp.net 如何修复此错误?
嗨,我正在尝试在树视图中实现数据库记录,比如父级和子级(表)。在运行时,我的连接字符串中出现错误 错误行:-Asp.net 如何修复此错误?,asp.net,sql,Asp.net,Sql,嗨,我正在尝试在树视图中实现数据库记录,比如父级和子级(表)。在运行时,我的连接字符串中出现错误 错误行:- string connectionstring = ConfigurationManager.ConnectionStrings["Data Source=ASDF;Initial Catalog=dbtree;Integrated Security=True"].ConnectionString; 错误是:- System.NullReferenceException was unh
string connectionstring = ConfigurationManager.ConnectionStrings["Data Source=ASDF;Initial Catalog=dbtree;Integrated Security=True"].ConnectionString;
错误是:-
System.NullReferenceException was unhandled by user code
Object reference not set to an instance of an object.
注意:-在我的数据库中,没有字段为空
代码:-
string connectionstring = ConfigurationManager.ConnectionStrings["Data Source=ASDF;Initial Catalog=dbtree;Integrated Security=True"].ConnectionString;
SqlConnection mycon = new SqlConnection(connectionstring);
mycon.Open();
SqlCommand mycmd = new SqlCommand("Select * from tbl_Parent", mycon);
SqlDataReader dr = mycmd.ExecuteReader();
mycmd.Dispose();
string[,] ParentNode = new string[100, 2];
int count = 0;
while (dr.Read())
{
ParentNode[count, 0] = dr.GetValue(dr.GetOrdinal("Parent_id")).ToString();
ParentNode[count++, 1] = dr.GetValue(dr.GetOrdinal("Parent_name")).ToString();
}
dr.Close();
您的连接字符串行不正确。它正在web.config中查找名为
"Data Source=ASDF;Initial Catalog=dbtree;Integrated Security=True".
由于该节点(显然)不存在,它将返回null
,您将得到一个异常
我猜你只是想:
string connectionstring = "Data Source=ASDF;Initial Catalog=dbtree;Integrated Security=True";
但是如果没有更多的上下文,我无法确定。您的连接字符串行不正确。它正在web.config中查找名为
"Data Source=ASDF;Initial Catalog=dbtree;Integrated Security=True".
由于该节点(显然)不存在,它将返回null
,您将得到一个异常
我猜你只是想:
string connectionstring = "Data Source=ASDF;Initial Catalog=dbtree;Integrated Security=True";
但是没有更多的上下文,我无法确定。替换
string connectionstring = ConfigurationManager.ConnectionStrings["Data Source=ASDF;Initial Catalog=dbtree;Integrated Security=True"].ConnectionString;
与
或者使用连接字符串名称
string connectionstring = ConfigurationManager.ConnectionStrings["Name here"].ConnectionString;
更新:正如下面的评论员所建议的,您可以在web.config文件中找到连接字符串的名称。Replace
string connectionstring = ConfigurationManager.ConnectionStrings["Data Source=ASDF;Initial Catalog=dbtree;Integrated Security=True"].ConnectionString;
与
或者使用连接字符串名称
string connectionstring = ConfigurationManager.ConnectionStrings["Name here"].ConnectionString;
更新:正如下面的评论员所建议的那样,您可以在web.config文件中找到连接字符串的名称。您正在使用字符串作为键对数组进行索引,但那里没有对象。这与数据库字段无关。您正在使用字符串作为键对数组进行索引,但没有对象。这与数据库字段无关。