This is most likely due to Workflow and/or Versioning being enabled. When you have either of those enabled, directly updating page data with a SQL statement will not update the version, only the page type data.
Your best bet is to create custom code (scheduled task) to execute this and use workflow and versioning to check the pages in and out and publish them. The second option is to take all those pages in workflow and remove them from workflow, then manually run the update, then add them all back in workflow again.