DbHelper groups logic around Db, tables, etc.

core/Controller.php

core/DataAccess/ArchiveTableCreator.php

core/Piwik.php

core/Session.php

core/Updates/0.2.27.php

core/Updates/0.2.33.php

core/Updates/0.5.5.php

core/View.php

index.php

misc/cron/archive.php

plugins/Actions/API.php

plugins/CoreAdminHome/Controller.php

plugins/CoreUpdater/Controller.php

plugins/CoreVisualizations/Visualizations/HtmlTable.php

plugins/DBStats/MySQLMetadataProvider.php

plugins/Goals/Controller.php

plugins/ImageGraph/API.php

plugins/Installation/Controller.php

plugins/LanguagesManager/Controller.php

plugins/Live/API.php