从数据库asp.net中获取数据
问题描述:
我试图让使用此代码从MS Access数据库中的数据,但我不能,这是我的代码这是正确的从数据库asp.net中获取数据
Dim query As String = "SELECT [data] FROM tabless WHERE user = '" & user.Text & "'"
Using connection As New OleDbConnection(connectionString)
Dim cmd As New OleDbCommand(query)
Dim adapter As OleDbDataAdapter = New OleDbDataAdapter(query, connection)
Dim com As New OleDbCommand(query, connection)
connection.Open()
'on the line below I get an error: connection property has not been initialized
Dim reader As OleDbDataReader = cmd.ExecuteReader()
While reader.Read()
Label1.Text = (reader(0).ToString())
End While
reader.Close()
End Using
数据库
|data|
asl
试图从数据库中获取数据并试图在标签中显示它是可能的
答
您从未将cmd
与连接关联,并且您n曾经使用com
或adapter
。这是你可以通过一行一行地逐行检查代码并检查其状态的方法。
Dim query As String = "SELECT [data] FROM tabless WHERE user = '" & user.Text & "'"
Using connection As New OleDbConnection(connectionString)
Dim cmd As New OleDbCommand(query, connection)
connection.Open()
Dim reader As OleDbDataReader = cmd.ExecuteReader()
While reader.Read()
Label1.Text = (reader(0).ToString())
End While
reader.Close()
End Using
此外,您的代码容易受到SQL注入攻击。您不应该将字符串连接在一起以形成查询。你应该改用参数化查询。
错误是什么?调试时会发生什么? – JKerny
'Dim reader As OleDbDataReader = cmd.ExecuteReader()' 连接属性尚未初始化 – Craftx398
该信息应该是您问题的一部分。请在此处进行修改,并意识到您需要在发布的每个问题中都包含这类信息。我们不应该问你这个问题。 – mason