ช่วยหน่อยนะคะ การเช็คข้อมูลในตารางว่ามีข้อมูลเดิมที่ตรงกับข้อมูลใหม่ที่Insert ไปหรือไม่น่ะค่ะ..

Dim sql_select As String
        sql_select = "SELECT ค่าที่ตรวจสอบ จะตรวจอะไรใส่ในช่องนี้นะคับ"
        Dim dr_select As OleDbDataReader
        Dim com_select As OleDbCommand
        com_select = New OleDbCommand()
        With com_select
            .CommandType = CommandType.Text
            .CommandText = sql_select
            .Connection = Conn
            .Parameters.Clear()
            dr_select = .ExecuteReader()
            If dr_select.HasRows Then
                ' ถ้ามีเเล้วให้ทำอะไร
            Else
                'ถ้าไม่มีเเล้วทำอะไร
            End If
        End With

Dim sql_select As String
        Dim dtNow As DateTime = System.DateTime.Now
        sql_select = "SELECT Date,Code_Tag,Pro_No FROM History_ReportCount WHERE Date='" & dtNow.ToString("MM/dd/yyyy") & "'"
        Dim dr_select As SqlDataReader
        Dim com_select As SqlCommand
        com_select = New SqlCommand()
        With myConn
            If .State = ConnectionState.Open Then .Close()
            .ConnectionString = StrConn
            .Open()
        End With
        With com_select
            .CommandType = CommandType.Text
            .CommandText = sql_select
            .Connection = myConn
            .Parameters.Clear()
            dr_select = .ExecuteReader()

            If dr_select.HasRows Then
                Dim Update As String
                Update = "UPDATE History_ReportCount SET Count_Scans= H.Count_Scans  +  P.Count_Scan "
                Update &= "FROM History_ReportCount H inner join Products_CodeTag P on H.Date = P.Date And H.Code_Tag = P.Code_Tag And H.Pro_No = P.Pro_No"

                With myConn
                    If .State = ConnectionState.Open Then .Close()
                    .ConnectionString = StrConn
                    .Open()
                End With
                Dim com As New SqlCommand
                With com
                    .CommandType = CommandType.Text
                    .CommandText = Update
                    .Connection = myConn
                    .ExecuteNonQuery()

                End With

            Else
                Dim Insert As String
                Insert = "INSERT INTO History_ReportCount (Date,Code_Tag,Pro_No,Count_Scans)"
                Insert &= "SELECT Date,Code_Tag,Pro_No,Count_Scan FROM Products_CodeTag"
                With myConn
                    If .State = ConnectionState.Open Then .Close()
                    .ConnectionString = StrConn
                    .Open()
                End With

                Dim com As New SqlCommand
                With com
                    .CommandType = CommandType.Text
                    .CommandText = Insert
                    .Connection = myConn
                    .ExecuteNonQuery()
                End With

            End If
        End With

        Dim update1 As String
        update1 = "UPDATE Products_CodeTag SET Count_Scan= '0' "
        With myConn
            If .State = ConnectionState.Open Then .Close()
            .ConnectionString = StrConn
            .Open()
        End With
        Dim com1 As New SqlCommand
        With com1
            .CommandType = CommandType.Text
            .CommandText = update1
            .Connection = myConn
            .ExecuteNonQuery()
        End With