最近使用sony Z5（android 7.0）手机开发app,先安装了数据库版本为26的app,然后卸载，想安装以前版本，发现一直无法安装，报错为数据库无法降级。
后来使用应用程序中的删除全部资料，再安装时发现可以正常安装。
所以猜测是数据库在app卸载时，没有及时卸载。
烦请帮忙确定此问题。谢谢！！！
Recently using the sony Z5 (android 7.0) mobile phone development app, first installed the database version of the 26 app, and then uninstall, want to install the previous version, found that has been unable to install, the error can not be downgraded database.
Later, the use of the application to delete all the information, and then found that the installation can be installed normally.
So guess is that the database was not unloaded in time when the app was uninstalled.
Please help determine this issue. Thank you! ! !
-GT
