select * from data where sn='221' order by id desc limit 4
idsntspqvaluesystemts
22761234 221 hum 47.50 1563677976 Sun 21 07 2019 04:59:36
22761233 221 temp 20.90 1563677976 Sun 21 07 2019 04:59:36
22761229 221 temp 20.90 1563677975 Sun 21 07 2019 04:59:35
22761228 221 hum 47.40 1563677975 Sun 21 07 2019 04:59:35

Sun Jul 21 04:59:59 2019 by walley