1 5 abc 2 6 bcd 1 7 ade 2 8 adc

result a b c 1 6 bcd 2 8 adc

select * from test where b in (select max(id) from test group by a)

select   t1.a,t1.b,t1.c from   test   t1   inner   join (seelct   a,max(b)   as   b   from   test   group   by   a)   t2   on   t1.a=t2.a   and   t1.b=t2.b

select   a,b,c from( select   a,b,c ,row_number()over(partition   by   a   order   by   b   desc)   rn from   test )   where   rn=1