我有一個 VB.NET 方法，它連接到資料庫并讀取值。并且這個值在多個地方被多次使用。該方法如下所示：
Public Function IsConfigurationEnabled() As Integer
Dim IsEnabled As Integer
Dim sqlText As String
sqlText = "select value from [dbo].[Settings] where Configuration='XXX'"
Dim connection As SqlConnection = New SqlConnection()
Dim cmd As SqlCommand
connection.ConnectionString = "Data Source=localhost;Initial Catalog=XXX;Integrated Security=True"
Try
connection.Open()
cmd = New SqlCommand(sqlText, connection)
IsEnabled = Convert.ToInt32(cmd.ExecuteScalar())
cmd.Dispose()
connection.Close()
Catch ex As Exception
AuditTrail(vbLogEventTypeError, "IsConfigurationEnabled :Error opening SQL Connection ")
End Try
Return IsEnabled
End Function
我只想連接到資料庫一次。
因為資料庫中的值永遠不會改變（或很少改變）。
有沒有辦法做到這一點？
uj5u.com熱心網友回復：
在呼叫代碼中存盤回傳值可能是最好的選擇。但是，您也可以使用延遲初始化，如下所示。
Public Function IsConfigurationEnabled() As Integer
Static isEnabled? As Integer
If isEnabled.HasValue Then
Return isEnabled.Value
End If
Dim sqlText As String = "select value from [dbo].[Settings] where Configuration='XXdX'"
Using connection = New SqlConnection()
connection.ConnectionString = "Data Source=localhost;Initial Catalog=Junk;Integrated Security=True"
Try
connection.Open()
Using cmd = New SqlCommand(sqlText, connection)
isEnabled = Convert.ToInt32(cmd.ExecuteScalar())
End Using
connection.Close()
Catch ex As Exception
AuditTrail(vbLogEventTypeError, "IsConfigurationEnabled :Error opening SQL Connection ")
End Try
End Using
Return IsEnabled
End Function
在實際專案中使用上述代碼會引起爭議，但我希望它具有指導意義。
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標籤：sql服务器VB.net