The Content with Style blog has a gotcha that Zend Framework developers could come across if they're using MySQL pre-5.17:

was getting weird errors when running multiple queries with Zend Framework, that I just couldn't replicate on my local environment. [...] Turns out the server runs MySQL pre 5.17.

This caused a stack trace error where the queries wouldn't run correctly. The solution was (like the error message suggests) turning on query buffering with the "PDO::MYSQL_ATTR_USE_BUFFERED_QUERY" in the PDO connection's parameters. You can find out more information about the parameters you can pass to the adapter in this section on the Zend Framework' Zend_Db manual page.