explain
SELECT ravenmon.* FROM (SELECT MAX(b.id) AS max_id FROM ravenmon b GROUP BY b.name) AS sub JOIN ravenmon ON max_id = id
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 8
1 PRIMARY ravenmon eq_ref PRIMARY PRIMARY 4 sub.max_id 1
2 DERIVED b range NULL name_2 52 NULL 9 Using index for group-by
8 total, Query took 0.0017 sec
---
explain
SELECT a.id, a.name, a.received, a.oper, a.cell, a.signal, a.net, a.ip, a.usage_day, a.usage_week, a.usage_month
FROM ravenmon a LEFT JOIN ravenmon b ON (b.name=a.name AND a.id<b.id) WHERE b.id IS NULL
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE a ALL NULL NULL NULL NULL 3805
1 SIMPLE b ref PRIMARY,name_2,name name_2 52 alive.a.name 468 Using where; Using index; Not exists
8 total, Query took 1.7258 sec