Id	useridgf	devid	gftime
				336713	1305951011	01529ba309386f8558245cb5c3f9d95e	2019-07-01 23:27:19
				1355366	1458275653	5213efd414b04f2869d20b7217d44c0f	2019-07-02 23:27:19
				1355368	5300482217	5213efd414b04f2869d20b7217d44c0f	2019-07-19 23:27:19
				1495736	1305768041	01529ba309386f8558245cb5c3f9d95e	2019-07-19 23:27:19

create table gftmp_duoyu SELECT t1.* FROM dev_user as t1,dev_user as t2 where t1.devid=t2.devid and t1.useridgf<>t2.useridgf and t1.gftime <= t2.gftime;
useridgf 加index

DELETE dev_user,gftmp_duoyu FROM dev_user,gftmp_duoyu where dev_user.useridgf = gftmp_duoyu.useridgf