( )方法可以获取对SQLite数据只读的数据库对象。P228
A.
onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion)
B.
openDatabase("testdemo", null, SQLiteDatabase.OPEN_READWRITE) in SQLiteDatabase
C.
getReadableDataBase() in SQLiteOpenHelper
D.
getWritableDatabase() in SQLiteOpenHelper