Question

嗨，大家好，如果数据库中存在相同的Id，我会尝试发送消息。但If语句不适用于OleDb.OleDbDataAdapte 如何解决这个问题并使If语句有效？

If Da1 = New OleDb.OleDbDataAdapter("select * from Payments where BookingID = " &
         CInt(txtBookingID.Text) & "", Con1) Then

     MessageBox.Show("This Bill for this Booking is existed in the system. 
     You Can not add it again.", "Authentication Failure", MessageBoxButtons.OK,
     MessageBoxIcon.Exclamation)

else 

    new_rec("BookingID") = txtBookingID.Text
    new_rec("DateAndTime") = lblDateAndTime.Text

    Dt1.Rows.Add(new_rec)
    Da1.Update(Dt1)

    MessageBox.Show("Booking ID " + " *" + txtBookingID.Text + "*  " + 
    "has been Saved to The System.      Press * OK * to Go Back")

end if

Answer 1

试试这个

 Da1 = New OleDb.OleDbDataAdapter("select * from Payments", Con1)

da1.Fill(dt1)

If dt1 is nothing orelse dt1.select("boolingid=" & txtBookingID.Text).count > 0  Then

    MessageBox.Show("This Bill for this Booking is existed in the system. You 
    Can not add it again.", "Authentication Failure", MessageBoxButtons.OK,
    MessageBoxIcon.Exclamation)

else 

    new_rec("BookingID") = txtBookingID.Text
    new_rec("DateAndTime") = lblDateAndTime.Text

    Dt1.Rows.Add(new_rec)
    Da1.Update(Dt1)

    MessageBox.Show("Booking ID " + " *" + txtBookingID.Text + "*  " + 
    "has been Saved to The System.  Press * OK * to Go Back")
end if

如何避免在vb中添加两次

1 个答案: