mysql 中关于怎么写 row_number()over(order by) 类似的功能支持

官网说明类似的支持：http://www.mysqltutorial.org/mysql-row_number/
根据说明排序 　　再根据条件判断是否一致 　　来决定是否新增 1

SELECT b.* FROM (
    SELECT 
        (@row_number :=
        CASE WHEN @region_id = region_id AND @oil_id = oil_id THEN 
        @row_number + 1 ELSE 1
        END 
        ) AS rn,

        id,
        oil_date,

        (@region_id := region_id) AS region_id,
        (@oil_id := oil_id) AS oil_id ,
        last_update_time
    FROM 
        `bwoil_prod_oil_price` s,
        (SELECT @row_number:=0) AS t
    WHERE audit_status=1 AND STATUS =0 
    ORDER BY region_id,oil_id ,oil_date DESC,last_update_time DESC

) a 
INNER JOIN `bwoil_prod_oil_price` b ON a.id = b.id
WHERE a.rn = 1