select claim_time from f3rpt.F3_TB_DAILY_FABOUT ; claim_time 倒序

以下是查询语句：

SELECT claim_time FROM f3rpt.F3_TB_DAILY_FABOUT ORDER BY claim_time DESC;

这将会按照 `claim_time` 字段的倒序（即从大到小）返回 `f3rpt.F3_TB_DAILY_FABOUT` 表中的所有 `claim_time` 值。

相关问题

(select date(a.claim_time) as date, a.lot_id, a.lot_type,a.mainpd_id,a.prodspec_id,a.custprod_id, case when(date(b.created_time) <= '2009-01-05') then b.created_time + 21 days else b.created_time end as created_time, CASE WHEN A.CUST_id in ('MCA','NPA','SET') THEN a.COMPLETE_TIME ELSE a.COMPLETE_TIME END COMPLETE_TIME, a.cust_id as customer_id, a.ope_category, c.layer From f3rpt.F3_TB_DAILY_FABOUT a, f3rpt.fvlot b, (select mainpd_id, sum(masks)layer from f3rpt.ASMCRPT_VW_MAINPD_MASKS_ALL group by mainpd_id) as c, (select * from (select lot_id, max(claim_time)claim_time, count(case when(ope_category='Ship')then lot_id else null end) as LS, count(case when(ope_category='Unship') then lot_id else null end) as LUS from f3rpt.F3_TB_DAILY_FABOUT where substr(lot_id,1,2) not in('CA','CW','ES','E0','EM') and lot_type = 'Production' AND LOT_ID NOT LIKE 'H%' and substr(lot_id,7,4)='.00F' and ope_category in ('Ship','Unship') and year(claim_time) = year(current date - 1 days) and month(claim_time) = month(current date - 1 days) group by lot_id) as a where LS - LUS > 0 ) as lot Where a.lot_id = b.lot_id and b.mainpd_id = c.mainpd_id and a.lot_id = lot.LOT_ID and a.claim_time = lot.claim_time and a.ope_category = 'Ship' and a.cust_id in ('SM','BOE','GSC','NPA','GTA') ) as lot_hs 以上嵌套子查询，请拆分下

面的嵌套子查询，以便更好地理解和优化该查询。

首先，最外层的查询选择了一些列并从其他查询中选择了一些数据，其中最重要的是日期、批次ID、批次类型、主产品ID、产品规格ID、客户产品ID、创建时间、完成时间、客户ID、操作类别和层。这些信息都是从其他查询中获取的。

接下来，我们来看第一个子查询：

select mainpd_id, sum(masks)layer from f3rpt.ASMCRPT_VW_MAINPD_MASKS_ALL group by mainpd_id

该子查询从 `f3rpt.ASMCRPT_VW_MAINPD_MASKS_ALL` 表中获取主产品ID和层信息，并将其按主产品ID分组。

接下来是第二个子查询：

select lot_id, max(claim_time)claim_time, count(case when(ope_category='Ship')then lot_id else null end) as LS, count(case when(ope_category='Unship') then lot_id else null end) as LUS
from f3rpt.F3_TB_DAILY_FABOUT
where substr(lot_id,1,2) not in('CA','CW','ES','E0','EM')
and lot_type = 'Production' AND LOT_ID NOT LIKE 'H%'
and substr(lot_id,7,4)='.00F'
and ope_category in ('Ship','Unship')
and year(claim_time) = year(current date - 1 days)
and month(claim_time) = month(current date - 1 days)
group by lot_id

该子查询从 `f3rpt.F3_TB_DAILY_FABOUT` 表中获取批次ID、要求时间、已发运批次数和未发运批次数，并将其按批次ID分组。该子查询还应用了一些过滤条件，例如要求时间在特定日期之前、批次类型为生产、批次ID不以特定字符串开头等。

最后，最外层的查询将这些子查询组合在一起，并应用了一些其他过滤条件，例如操作类别为发运、客户ID为特定值等。

拆分这个查询的好处是，可以更好地理解每个子查询的作用和结果，并且可以更容易地对查询进行优化，例如通过添加索引来提高性能。

select lot_hs.lot_id as lot_id,lot_type,lot_hs.mainpd_id, created_time,COMPLETE_TIME, value(bank.banktime,0) as banktime , round ( ( 1.00*(days(COMPLETE_TIME)-days(created_time)) + (hour(COMPLETE_TIME)-hour(created_time))*1.00/24 + (minute(COMPLETE_TIME)-minute(created_time))*1.00/24/60 + (second(COMPLETE_TIME)-second(created_time))1.00/24/60/60) - value(bank.banktime,0),3) as use_days, customer_id, coalesce(cc.cust_id_define,lot_hs.customer_id) as cust_id2, cc.cycletime_target as ct_target, date,layer, round(count() over(partition by coalesce(cc.cust_id_define,lot_hs.customer_id),cc.cycletime_target)*0.9,0) cnt, row_number() over(partition by coalesce(cc.cust_id_define,lot_hs.customer_id),cc.cycletime_target order by ( ( days(COMPLETE_TIME)-days(created_time) + (hour(COMPLETE_TIME)-hour(created_time))*1.00/24 + (minute(COMPLETE_TIME)-minute(created_time))*1.00/24/60 + (second(COMPLETE_TIME)-second(created_time))*1.00/24/60/60) - value(bank.banktime,0))/layer) id From (select date(a.claim_time) as date, a.lot_id, a.lot_type,a.mainpd_id,a.prodspec_id,a.custprod_id, case when(date(b.created_time) <= '2009-01-05') then b.created_time + 21 days else b.created_time end as created_time, CASE WHEN A.CUST_id in ('MCA','NPA','SET') THEN a.COMPLETE_TIME ELSE a.COMPLETE_TIME END COMPLETE_TIME, a.cust_id as customer_id, a.ope_category, c.layer From f3rpt.F3_TB_DAILY_FABOUT a, f3rpt.fvlot b, (select mainpd_id, sum(masks)layer from f3rpt.ASMCRPT_VW_MAINPD_MASKS_ALL group by mainpd_id) as c, (select * from (select lot_id, max(claim_time)claim_time, count(case when(ope_category='Ship')then lot_id else null end) as LS, count(case when(ope_category='Unship') then lot_id else null end) as LUS from f3rpt.F3_TB_DAILY_FABOUT where substr(lot_id,1,2) not in('CA','CW','ES','E0','EM') and lot_type = 'Production' AND LOT_ID NOT LIKE 'H%' and substr(lot_id,7,4)='.00F' and ope_category in ('Ship','Unship') and year(claim_time) = year(current date - 1 days) and month(claim_time) = month(current date - 1 days) group by lot_id) as a where LS - LUS > 0 ) as lot Where a.lot_id = b.lot_id and b.mainpd_id = c.mainpd_id and a.lot_id = lot.LOT_ID and a.claim_time = lot.claim_time and a.ope_category = 'Ship' and a.cust_id in ('SM','BOE','GSC','NPA','GTA') ) as lot_hs left outer join (select lot_id,max(bankin_time) banktime from f3rpt.asmc_dpm where bankin_time>0 group by lot_id) bank on (lot_hs.lot_id = bank.lot_id) left join f3cim.f3cim_cfg_cust_rule cc on case when lot_hs.customer_id='WXM' THEN 'WII'||SUBSTR(lot_hs.mainpd_id,6,1) else lot_hs.customer_id end = cc.cust_id and locate(cc.mainpd_id,lot_hs.mainpd_id)>0 and locate(cc.prodspec_id,lot_hs.prodspec_id)>0 and locate(cc.custprod_id_45,substr(lot_hs.custprod_id,3,3))>0 where lot_hs.ope_category = 'Ship' ；以上sql如何优化

这是一个比较复杂的 SQL 语句，可以从以下几个方面考虑进行优化：

1.使用 JOIN 替代子查询

可以使用 JOIN 语句替代子查询，可以提高查询效率。例如，将以下子查询：

(select mainpd_id, sum(masks)layer from f3rpt.ASMCRPT_VW_MAINPD_MASKS_ALL group by mainpd_id) as c

改写为：

FROM f3rpt.ASMCRPT_VW_MAINPD_MASKS_ALL c GROUP BY mainpd_id

2.使用索引

对于频繁查询的字段，可以添加索引以提高查询效率。例如，可以为以下字段添加索引：

b.mainpd_id
a.lot_id
a.cust_id
lot_hs.customer_id
cc.cust_id_define
cc.mainpd_id
cc.prodspec_id
cc.custprod_id_45

3.使用 EXPLAIN 分析查询计划

使用 EXPLAIN 命令可以分析查询计划，了解查询语句的执行情况，从而优化查询语句以提高查询效率。

4.使用 UNION 替代多个 OR 条件

对于多个 OR 条件的查询语句，可以使用 UNION 来代替，可以提高查询效率。例如：

AND lot_type = 'Production' AND LOT_ID NOT LIKE 'H%' and substr(lot_id,7,4)='.00F' and ope_category in ('Ship','Unship')

可以改写为：

AND lot_type = 'Production' AND LOT_ID NOT LIKE 'H%' and substr(lot_id,7,4)='.00F' and ope_category = 'Ship'
UNION
AND lot_type = 'Production' AND LOT_ID NOT LIKE 'H%' and substr(lot_id,7,4)='.00F' and ope_category = 'Unship'