For me it seems like the data is not correctly read from the database, so maybe a database issue?
Try to find the source of the issue by first cloning database and osticket install. Next make sure the osticket config file (if I remember right it's under /include/ost_config.php) points to the cloned database. Next is to replace the osticket installation files with the ones from the original 1.9.1 download package (www.osticket.com/download). If you now see the tickets, replacing the files on your original system should solve the problem. In case you still do not see any tickets you at least know it's an database issue. Unfortunately I can't tell you exactly what's wrong with your database since I have not enough played around with such database errors, but then maybe @[deleted] or is able to help.
So please try with a cloned installation + database and let us know how the clone behaves.
Cheers,
Michael
PS:
@[deleted]
Isn't cdata some kind of caching table inside the osticket database? Referring to the following part of the error message which seems for me to be the interesting one at that whole error message: Unknown column 'cdata.subject' in 'field list'