public bool IsOpticalSerialNoExisting(bool isOpticalSerialNoExisting = false)
{
MarikinaOpticalEntities dbContext = new MarikinaOpticalEntities();
var opticalSerialNo = dbContext.GetSerialNumberOpticalRx(txtSerialNo.Text);
foreach (var number in opticalSerialNo)
{
isOpticalSerialNoExisting = true;
}
return(isOpticalSerialNoExisting);
}