In my application, I have a database that gets written out to the sdcard. We have had to make a lot of big cha开发者_运维问答nges to the database, so when the user upgrades the application, is there a way to delete and reinstall the database, but only on upgrade?
The best way to do this is to have a chunk of code in the upgrade that checks for the old database and if it finds an old database, do the upgrade.
This lets you control what happens, and also how it happens.
央视是哪个频道西非利 33分钟前 来自北京1、央视一共有15个频道，分别是：CCTV-1综合频道、CCTV-2财经频道、CCTV-3综艺频道、CCTV-4中文国际频道、CCTV-5体育频道、CCTV-6电影频道、CCTV-7军事·农业频道、CC
请问买过的朋友，舒提啦旅行箱实际使用体验如何？
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103010正在紧张有序的拍摄中，恰逢演员王昌瑞的生日。现场工作人员为他庆生，主演也送上祝福。
It seems to me Apple won\'t allow this, but I need to make sure. For an app we\'re building, we want to ask the user to enter payment information (including credit card details) to pay for tickets. T
I need to generate an XML output using Perl code.I\'m trying not to use any libraries,as it\'s very simple, temporary XML that gets used by another step in the process.
是否在对方手机上显示已读，是由用户自行设置的。依次打开iPhone的“设置-信息”，会有一个“发送已读回执”的选项。将其打开，对方就能看到你，是否已经阅读了本条iMessage信息。将其关闭，对方就看不到。
微信重新建群怎么开发者_Go百科建？ 产品名称：苹果手机 产品型号：iPhone 11 系统版本：iOS 13
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