Дальше на инглише:
I`m lazy programmer. I do not wanna spent time to figure out with compiling some additional qt plugins when my goal is just get working application from the just downloaded sources. The easy way is find somewhere binaries for Qt 4.6 mysql plugin. It`s a pity I did not find these binaries. So I build them myself. You can download ready for use Qt 4.6 MySQL plugin from this page (attachments in the bottom)
Visual Studio 2008
MySQL 5.1 (headers and lib from mysql 5.1.41)
How to use:
put \sqldrivers and libmysql.dll next to you executable.