select * from data where sn='221' and pq='temp' order by id desc limit 4
idsntspqvaluesystemts
20702604 221 temp 16.60 1558463275 Tue 21 05 2019 20:27:55
20702599 221 temp 16.70 1558463274 Tue 21 05 2019 20:27:54
20702587 221 temp 16.60 1558463255 Tue 21 05 2019 20:27:35
20702581 221 temp 16.60 1558463235 Tue 21 05 2019 20:27:15

Tue May 21 20:27:58 2019 by walley