“系统无法建立连接”

Question

我对我的连接有疑虑，即使我的数据库连接已打开，也无法建立连接。我把所有正确的字符串建立起来但没有连接。此代码应该为特定系统登录用户。

Imports MySql.Data.MySqlClient
Module SQLConn
Public ServerMySQL As String
Public PortMySQL As String
Public UserNameMySQL As String
Public PwdMySQL As String
Public DBNameMySQL As String
Public sqL As String
Public ds As New DataSet()
Public cmd As MySqlCommand
Public dr As MySqlDataReader
Public da As New MySqlDataAdapter

Public conn As New MySqlConnection

Sub getData()
    Dim AppName As String = Application.ProductName

    Try
        DBNameMySQL = GetSetting(AppName, "DBSection", "DB_Name", "temp")
        ServerMySQL = GetSetting(AppName, "DBSection", "DB_IP", "temp")
        PortMySQL = GetSetting(AppName, "DBSection", "DB_Port", "temp")
        UserNameMySQL = GetSetting(AppName, "DBSection", "DB_User", "temp")
        PwdMySQL = GetSetting(AppName, "DBSection", "DB_Password", "temp")
    Catch ex As Exception
        MsgBox("System registry was not established, you can set/save " & _
        "these settings by pressing F1", MsgBoxStyle.Information)
    End Try

End Sub

Public Sub ConnDB()
    conn.Close()
    Try
        conn.ConnectionString = "Server = '" & ServerMySQL & "';  " _
                                     & "Port = '" & PortMySQL & "'; " _
                                     & "Database = '" & DBNameMySQL & "'; " _
                                     & "user id = '" & UserNameMySQL & "'; " _
                                     & "password = '" & PwdMySQL & "'"

        conn.Open()
    Catch ex As Exception
        MsgBox("The system failed to establish a connection", MsgBoxStyle.Information, "Database Settings")
    End Try

End Sub

Public Sub DisconnMy()

    conn.Close()
    conn.Dispose()

End Sub

Sub SaveData()
    Dim AppName As String = Application.ProductName

    SaveSetting(AppName, "DBSection", "DB_Name", DBNameMySQL)
    SaveSetting(AppName, "DBSection", "DB_IP", ServerMySQL)
    SaveSetting(AppName, "DBSection", "DB_Port", PortMySQL)
    SaveSetting(AppName, "DBSection", "DB_User", UserNameMySQL)
    SaveSetting(AppName, "DBSection", "DB_Password", PwdMySQL)

    MsgBox("Database connection settings are saved.", MsgBoxStyle.Information)
End Sub



 End Module

有人可以帮忙吗？感谢