If you installed both then it is probably confusing CMake and you need to set the LIBs manually:
Open CMake and set your build / source directories
Click File -> Delete Cache and answer Yes
Click Tools -> Configure
Choose Specify Native Compilers and click Next
Browse to "cl.exe" for both the C and C++ compiler
Click Finish
When it's done configuring, go to step 10
Uncheck USE_MYSQL_SOURCES and click Configure again
Check the Advanced option
Look for MYSQL_INCLUDE_DIR and point this to C:/Program Files/MySQL/5.5/include or wherever you installed MySQL Community Edition
Look for MYSQL_LIBRARY and point this to C:/Program Files/MySQL/5.5/lib/libmysql.lib or wherever you installed MySQL Community Edition
Click Configure
Click Generate
You're done!