ExecuteReader需要一個開放且可用的Connection。連接的當前狀態是開放

Question

我目前得到的錯誤：

ExecuteReader requires an open and available Connection. The connection's current state is open.

這裏是我的代碼：

班db.conn

Public Class db 
    Public Shared conn As SqlConnection = db.getsqlconn("ezondb") 



    Public Shared Function getsqlconn(ByVal whichdb As String) As SqlConnection 
     Dim connstring As String = ConfigurationManager.ConnectionStrings(whichdb).ConnectionString 
     Return New SqlConnection(connstring) 
    End Function 



Dim Macomm = db.selectcommand(db.conn, "*", "categories", "idparentcategory=1") 
Dim Mada As New SqlDataAdapter(Macomm) 
Dim Mat As New DataTable 
Mada.Fill(Mat) 

Answer 1

我不會聲明co nnections爲Shared：

Public Shared conn As SqlConnection = db.getsqlconn("ezondb") 

打開，當你需要它，之後將其關閉的連接。

Answer 2

的getsqlconn方法只是返回sqlconnection對象的新實例，您需要通過調用open方法明確打開連接