Greendao Android Open source framework database Update table issues

Recently used Greendao when Android app upgraded database new table or modified table, found the problem of data being emptied

Find the material also did not find the solution, finally see Code discovery need to modify Sqliteopenhelper

1. Find the Greendao generated Daomaster.java file with Sqliteopenhelper implementation

2. Modify the public void Onupgrade (sqlitedatabase db, int oldversion, int newversion) method in the Devopenhelper class

by Oldversion NewVersion to determine the need to create a table or ALTER TABLE

(originally thought that the code generated by Greendao will automatically complete this step.)