Question

Private Sub View_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    ''Search All data

    Dim Reader As MySqlDataReader
    Dim Query As String

    Try
        myConn.Open()


        Query = "SELECT*FROM datainfo"
        myComman = New MySqlCommand(Query, myConn)

        Reader = myComman.ExecuteReader

        While Reader.Read
            Dim sName = Reader.GetString("StudentName")
            ComboBox1.Items.Add(sName)
        End While

    Catch ex As Exception
        MessageBox.Show(ex.Message)

    Finally
        myConn.Dispose()

    End Try

Answer 1

声明数据连接myConn的方式不完整。有很多关于如何通过快速谷歌搜索来做到这一点的例子。如果您在配置文件中定义了连接，那么它将是：

Dim myConn as New SqlConnection(configurationManager.ConnectionStrings("MyConn").ConnectionString)

在不相关的说明中，您将要关闭数据库连接并处理该命令。所以

Finally   
  myConn.close()
  myComman.dispose()

垃圾收集器会自动为您处理该命令，但不会自行处理任何事情。

连接必须有效或开放

1 个答案: