PostNuke uses ADODB library, and the best idea is using this stuff in all additional blocks and modules. In some blocks (4 e.g.) i found calling direct to mysql_query php function. I think - it's bad style. using ADODB is preferred;
In some blocks I had to correct this stuff - replace this with $result=$dbconnect->Execute('..'). But not all PostNuke users have necessary knowledge to doing this.
direct calling to php database functions is bad style;