I'm using the KyngChaos builds on OSX which doesn't have MySQL support.
I found a thread  from July, 2015 where William said "I haven't packaged
a GDAL plugin for MySQL yet, it's on my list of things to do but it's not
very high priority."
I just wanted to add a patient request for this to happen and see where it
stands on the priority list these days.
I've been working on adding some lightweight spatial capabilities to the
WordPress CMS, which uses MySQL as its database. What I'm doing isn't
intensive GIS, by any means, but it would be really convenient to be able
to quickly visualize and modify the data I'm working with in QGIS.
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