string TaoMoiMaPhieu()
{
PhieuMuonDAO pm = new PhieuMuonDAO();
string old = pm.GetMaxMaPhieu();
old = old.TrimStart('P');
int newCode = int.Parse(old);
newCode += 1;
string code = "P";
if (newCode < 10)
{
code = code + "00" + newCode;
}
else if (newCode < 100)
{
code = code + "0" + newCode;
}
else
{
code = code + newCode;
}
return(code);
}