Constant: add common constant file

Add common constant file to integrate dispersed constants in one file.

Signed-off-by: likeusmoment <likeusmoment@gmail.com>
DB: add integration class to hold all kinds of database objects in an object

add integration class to hold all kinds of database objects in an object

Signed-off-by: likeusmoment <likeusmoment@gmail.com>
db: modify db connector

1. bugfix in creating tables
2. add select all from db about author, book
3. add the function to insert testcases to DB

Signed-off-by: likeusmoment <likeusmoment@gmail.com>
listview: modify listview to get data from db

modify listview to get data from db

Signed-off-by: likeusmoment <likeusmoment@gmail.com>
layout: add a layout for a row in listview for testing

add a layout for a row in listview for testing

Signed-off-by: likeusmoment <likeusmoment@gmail.com>