This contribution provides methods to correct various issues in a Zen Cart® database as well as a means to convert a database to now-current database collations, e.g. utf8 and the more-preferable utf8mb4.
Zen Cart Support Thread: https://www.zen-cart.com/showthread.php?219246
Zen Cart Download: https://www.zen-cart.com/downloads.php?do=file&id=2367
Refer to the readme.html in this GitHub repository for additional details.