分组后A列最大的B列

分组后A列最大的B列 ，分组:employee_id  A列:log_date   B列:old_salary  

select * from "plch_emp_log" order BY "employee_id","log_date";

select "employee_id",
replace(lpad('123',4),' ','0'),
min("log_date"),
MIN("old_salary") KEEP(DENSE_RANK FIRST ORDER BY "log_date"),
TO_NUMBER(SUBSTR(MIN(TO_CHAR("log_date",'YYYYMMDDHH24MISS')||"old_salary"),15)),-- 分组后，取log_date最小记录的old_salary
"SUM"("new_salary")
from "plch_emp_log" GROUP BY "employee_id";