oracle 分组取第一行数据 ，查询sql语句

oracle  分组取第一行数据

SELECT * FROM (

SELECT ROW_NUMBER() OVER(PARTITION BY x ORDER BY y DESC) rn,
t.*
FROM test1 t
) WHERE rn = 1;

查找oracle  执行的语句 

select t.*
from v$sqlarea t
where t.FIRST_LOAD_TIME like '2018-11-05%'
order by t.FIRST_LOAD_TIME desc