select * from data where sn='221' order by id desc limit 4
idsntspqvaluesystemts
39739359 221 hum 30.70 1594699055 Tue 14 07 2020 05:57:35
39739358 221 temp 19.30 1594699055 Tue 14 07 2020 05:57:35
39739354 221 hum 30.80 1594699036 Tue 14 07 2020 05:57:16
39739353 221 temp 19.30 1594699036 Tue 14 07 2020 05:57:16

Tue Jul 14 05:57:47 2020 by walley