select * from data where sn='ds1' order by id desc limit 4
idsntspqvaluesystemts
27201347 ds1 temp 17.50 1571624861 Mon 21 10 2019 04:27:41
27201341 ds1 temp 17.50 1571624839 Mon 21 10 2019 04:27:19
27201338 ds1 temp 17.50 1571624817 Mon 21 10 2019 04:26:57
27201332 ds1 temp 17.50 1571624796 Mon 21 10 2019 04:26:36

Mon Oct 21 04:28:03 2019 by walley