Processing files which are obviously organized in sections, chunks whatever you want to call it, happens and trying to find elements in it in an AND relationship is my most common use case. Sadly grep does not seem to have a nice way of processing based on a separator, but purely goes by line, so the easy way around this is to join all the lines in a chunk and grep in the result. Think input like this

SECTION
foo=bar
xyz=111
baz=blob
SECTION
foo=1
bat=man
baz=3

Some AWK magic does the joining trick,

awk '/SECTION/ {printf "\n%s\n",$0;next} {printf "%s ",$0} END {print "\n"}' INPUT_FILE

And now

awk '/SECTION/ {printf "\n%s\n",$0;next} {printf "%s ",$0} END {print "\n"}' INPUT_FILE | \
grep 'foo=bar' | \
grep 'baz=blob'

Gives the matching section.