oracle 分组排序：
这个麻烦：
SELECT * FROM (
SELECT deptno,ename,sal,ROW_NUMBER() OVER (PARTITION BY deptno ORDER BY sal DESC ) Top3 FROM emp
)
WHERE Top3 <= 3
开窗函数也ok：代码简单点：
where 1=1 and status=2
JOIN( select pid,min(id) as id from T_PRODUCT group by pid) firstp ON firstp.id=p.id
mybatis应用：
where 1=1 and status=2
JOIN( select pid,min(id) as id from T_PRODUCT WHERE STATUS=2 and LIFESTATUS > 0 group by pid) firstp ON firstp.id=p.id
分组最大最小：
min()/max() over(partition by pid order by id)
分组分页：
-- 使用ROW_NUMBER分页，查找第1-10条数据 SELECT T.custid,T.companyname,T.address,T.city FROM ( SELECT ROW_NUMBER() OVER(ORDER BY custid) AS rownum,custid,companyname,address,city FROM Sales.Customers ) AS TWHERE T.rownum BETWEEN 1 AND 10 促销选择商品应用例子： SELECT pp.*,PA.* FROM (select t.* from ( select p.id,p.productcode,p.introduce,p.delivery_address,p.reason,p.catalogID,p.name,p.picture,p.price,p.NowPrice,p.isnew,p.sale,p.hit,p.title,p.createAccount,to_char(p.createtime,'yyyy-MM-dd hh24:mi:ss') createtime,to_char(p.updatetime,'yyyy-MM-dd hh24:mi:ss') updatetime,b.between_price AS areaprice,p.status,p.sellcount,b.stock,p.giftID,p.images,(SELECT name FROM T_CATALOG cat WHERE cat.ID=p.CATALOGID) as catalogname,(SELECT unit FROM T_CATALOG cat WHERE cat.ID=p.CATALOGID) as unit,p.pid,p.packlisting,p.productplace,b.COUNTPID countpid,DENSE_RANK() OVER(ORDER BY p.pid) AS mrownum from t_product p join (select * from between_price_view where area_id ='331946' OR (area_id =0) ) b on b.pid=p.pid where 1=1 order by p.updatetime desc,p.id ) t where mrownum <= 0+20 ) pp LEFT JOIN ( SELECT * FROM (select productid,area_id,price from T_PRICE_AREA) PIVOT ( sum(price) FOR area_id IN (331518,331946,333168) )) pa ON pa.PRODUCTID = pp.id where pp.mrownum >10
