将PHP版本从4更改为5后，我遇到了一些问题。 我不得不将旧的mysql函数替换为mysqli。现在我得到下面的错误。 我找不到任何错误。我尝试使用or die（mysqli_error（$ xyz））进行调试，但是未定义的变量只有错误。 查找错误代码的最佳方法是什么？我认为数据库连接有问题。
E_NOTICE Error in file �index-test.php� at line 547: Undefined variable: JID
E_NOTICE Error in file �index-test.php� at line 553: Undefined variable: online
E_NOTICE Error in file �index-test.php� at line 557: Undefined variable: international
E_NOTICE Error in file �index-test.php� at line 558: Undefined variable: HH
E_NOTICE Error in file �index-test.php� at line 560: Undefined variable: aus
E_NOTICE Error in file �index-test.php� at line 561: Undefined variable: dmc
E_NOTICE Error in file �index-test.php� at line 562: Undefined variable: hmc
E_NOTICE Error in file �index-test.php� at line 563: Undefined variable: ild2
E_NOTICE Error in file �index-test.php� at line 564: Undefined variable: housing
E_NOTICE Error in file �index-test.php� at line 565: Undefined variable: angebot_weg
E_NOTICE Error in file �index-test.php� at line 566: Undefined variable: vertrag_weg
E_NOTICE Error in file �index-test.php� at line 567: Undefined variable: vertrag_da
E_NOTICE Error in file �index-test.php� at line 569: Undefined variable: projektmanagement
E_NOTICE Error in file �index-test.php� at line 570: Undefined variable: EXHIBITIONREG
E_NOTICE Error in file �index-test.php� at line 571: Undefined variable: IMR
E_NOTICE Error in file �index-test.php� at line 572: Undefined variable: TNM
E_NOTICE Error in file �index-test.php� at line 573: Undefined variable: RefHandl
E_NOTICE Error in file �index-test.php� at line 574: Undefined variable: REGISTRATION2
E_NOTICE Error in file �index-test.php� at line 575: Undefined variable: GRUPPENREG2
E_NOTICE Error in file �index-test.php� at line 576: Undefined variable: BC
E_NOTICE Error in file �index-test.php� at line 577: Undefined variable: INDIV
E_NOTICE Error in file �index-test.php� at line 578: Undefined variable: GruppenHL
E_NOTICE Error in file �index-test.php� at line 579: Undefined variable: HotelKoord
E_NOTICE Error in file �index-test.php� at line 580: Undefined variable: Service
E_NOTICE Error in file �index-test.php� at line 581: Undefined variable: Service2
E_NOTICE Error in file �index-test.php� at line 582: Undefined variable: Service3
E_NOTICE Error in file �index-test.php� at line 583: Undefined variable: Service4
E_NOTICE Error in file �index-test.php� at line 585: Undefined variable: webiplan
E_NOTICE Error in file �index-test.php� at line 592: Undefined index: ildCodeSelect
E_NOTICE Error in file �index-test.php� at line 599: Undefined index: SucheNeu
E_NOTICE Error in file �index-test.php� at line 643: Undefined variable: clear
E_NOTICE Error in file �index-test.php� at line 646: Undefined variable: change
E_NOTICE Error in file �index-test.php� at line 695: Undefined variable: anlegen
E_NOTICE Error in file �index-test.php� at line 838: Undefined variable: such
E_NOTICE Error in file �index-test.php� at line 861: Undefined variable: ansicht
E_NOTICE Error in file �index-test.php� at line 865: Undefined variable: ansicht
E_NOTICE Error in file �index-test.php� at line 869: Undefined variable: ansicht
E_NOTICE Error in file �index-test.php� at line 873: Undefined variable: ansicht
E_NOTICE Error in file �index-test.php� at line 877: Undefined variable: ansicht
E_NOTICE Error in file �index-test.php� at line 881: Undefined variable: ansicht
E_NOTICE Error in file �index-test.php� at line 885: Undefined variable: ansicht