You're making progress... now you just need to tell it where to find your mysql libraries by adding to your perl Makefile.pm commandL

--cflags=-I/usr/local/mysql -libs=-L/path/to/mysql/libs
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You can find most of this information in the INSTALL.html file that's in the tio level of your DBD-mysql build directory -- if you continue to have difficulty, look for the answer there before posting here -- might save you a lot of time.