从选择查询mysql vb.net插入值数组

Question

I have an application that shows the shift target of a certain reference. I have a lot of references divided in 3 shifts (morning, afternoon, evening) The app is working good but now i want to reset the counter of the shift targets in the beginning of every shift for all references. I mean, when the clock is 6am, all the morning shift should put the counter on 0. I have the following code but is not working. Something is missing and i'm stuck.

Dim rtime As New TimeSpan(0, 0, CInt(requestddate.TimeOfDay.TotalSeconds))


        hora1 = New TimeSpan(6, 0, 0)
        hora2 = New TimeSpan(14, 0, 0)
        hora3 = New TimeSpan(22, 0, 0)

        ConnectDatabase()

        If rtime = hora1 Then

            count = 0

            Try

                With cmd4
                    .Connection = conn
                    .CommandText = "Select ShiftTarget.IDShiftTarget from ShiftTarget, turnos, linhas WHERE ShiftTarget.IDLinha = linhas.IDLinha and ShiftTarget.IDTurno = turnos.IDTurno And turnos.Descricao = 'Manha' And linhas.NomeLinha = '" & GlobalVariables.linha & "'"
                End With

                While objReader.Read()
                listaIDs.Add(objReader("IDShiftTarget").ToString())
            End While

            objReader.Close()

            DisconnectDatabase()

            ConnectDatabase()

            With cmd1
                .Connection = conn
                .CommandText = "INSERT into contador (IDShiftTarget, Data, Contador) VALUES (@ID, @date, @cont)"
                For Each item As String In listaIDs
                    MsgBox(item)
                    .Parameters.AddWithValue("@ID", item)
                    .Parameters.AddWithValue("@date", data.ToString("yyyy-MM-dd"))
                    .Parameters.AddWithValue("@cont", count)
                    .ExecuteNonQuery()
                Next
            End With

        Catch ex As Exception
            If ex.InnerException IsNot Nothing Then
                MsgBox(ex.InnerException)
            End If
        End Try

        DisconnectDatabase()

Can someone tell me what am i doing wrong?

Update: This is what i get (and it's expected) from the select query:

And this is the table where i want to reset the counter:

So, imagine, when the actual time is 6am, i want to insert something like:

IDContador   IDShiftTarget      Data      Contador
11933          32           2016-02-23       0
11934          19           2016-02-23       0
11935          20           2016-02-23       0
11936          35           2016-02-23       0

I cannot simply reset to 0 where idshifttarget is equal to 19,20,32,35 because that would reset all the records, and i want to keep them in the table. I need to check the MAX(ID) where the shiftTarget is the value i got in the array, and then put the Contador to 0.

UPDATE:

I have made this changes in the code:

While objReader.Read()
                listaIDs.Add(objReader("IDShiftTarget").ToString())
            End While

            objReader.Close()

            DisconnectDatabase()

            ConnectDatabase()

            With cmd1
                .Connection = conn
                .CommandText = "INSERT into contador (IDShiftTarget, Data, Contador) VALUES (@ID, @date, @cont)"
                For Each item As String In listaIDs
                    MsgBox(item)
                    .Parameters.AddWithValue("@ID", item)
                    .Parameters.AddWithValue("@date", data.ToString("yyyy-MM-dd"))
                    .Parameters.AddWithValue("@cont", count)
                    .ExecuteNonQuery()
                Next
            End With

        Catch ex As Exception
            If ex.InnerException IsNot Nothing Then
                MsgBox(ex.InnerException)
            End If
        End Try

        DisconnectDatabase()

With this code i can only see the first ID and in the console i get the next error: Exception thrown: 'System.InvalidOperationException' in MySql.Data.dll

Answer 1

There are some things in your code which lead to wrong havior:

• You cannot execute a CRUD action while looping thru a DataReader: Create a list to store IDShiftTargets , close the DataReader and then loop thru the list and execute the Insert statements.
• Take care that the data types of your DB columns match with the code data types (IDShiftTarget int/Integer, IDShiftTarget date/DateTime, ...).
• When using a prepared statement with bound parameters make sure that you use AddWithValue only once outside the loop and set it in the loop with Parameter("@ID").Value = item
• Since the code is executed in a timer event which ticks every second, it is
  likely that a first execution has not finished until the next timer ticks. If you want to run the code secure and synchron make sure that the current execution is not disturbed, eg setting Timer.Enabled= False at the beginning of the function and Timer.Enabled=True after function has finished. Or just set the timer tick high enough ( d'oh ).