[util][bug-fix] Fixed process for table join.
[test] Synced with new db format.
[cxxtags][bug-fix] Fixed file path normalizing process.
[util] Added process to normalize file path.
[refactore] Changed way to connect to database file.
[test] Synced with new db format.
[test] Synced with db format.
[cxxtags][bug-fix] Fixed the way to deal with empty file names.