select * from data where sn='221' and pq='temp' order by id desc limit 4
idsntspqvaluesystemts
27168270 221 temp 17.80 1571485046 Sat 19 10 2019 13:37:26
27168258 221 temp 17.80 1571485026 Sat 19 10 2019 13:37:06
27168254 221 temp 17.80 1571485025 Sat 19 10 2019 13:37:05
27168244 221 temp 17.80 1571485006 Sat 19 10 2019 13:36:46

Mon Oct 21 04:03:58 2019 by walley