我正在 Oracle 9 数据库中编写一个 View ,但我被难住了。我要解决的是:A_WPD_ADDRESS_HISTORY 包含一个名为 WPD_PLAN_CHECK_S 的 FK,并且此 View 包含此 FK 的多个地址。我正在尝试获取每个 WPD_PLAN_CHECK_S (FK) 的最新地址。您将使用 FIRST_INSERTED 列,这是该行首次插入的日期/时间,并在其上调用聚合函数 MAX(),但目前我只知道这些,因此我很困惑。
下面是我认为理解这个问题需要的两个主要观点。对于我目前正在尝试解决的问题,其他表/ View 与此问题无关。
下方:我正在尝试检索最近地址记录的主视图。
SELECT
awa.wpd_address_history_s,
wpc.wpd_plan_check_s,
wpc.pcis_display,
awa.street_num,
awa.street_frac,
awa.street_prefix,
awa.street_name,
awa.street_type_l_s,
awa.street_suffix,
awa.street_unit_l_s,
awa.street_unit_num,
awa.cross_streets,
awa.city,
awa.state,
awa.state_l_s,
awa.zip,
awa.zip_ext,
awa.zip_with_ext,
wf.ind_id,
wpc.wpd_status_l_s,
wsl.wpd_status_desc,
awa.location as LOCATION,
wc.contact_name
FROM
wpd_plan_check wpc
LEFT OUTER JOIN a_wpd_address_history awa ON wpc.wpd_plan_check_s = awa.wpd_plan_check_s
LEFT OUTER JOIN wpd_contact wc ON wpc.wpd_plan_check_s = wc.wpd_plan_check_s
LEFT OUTER JOIN wpd_facility wf ON wpc.wpd_plan_check_s = wf.wpd_plan_check_s
LEFT OUTER JOIN wpd_status_l wsl ON wpc.wpd_status_l_s = wsl.wpd_status_l_s
LEFT OUTER JOIN street_type_l stl ON awa.street_type_l_s = stl.street_type_l_s
LEFT OUTER JOIN street_unit_l sul ON awa.street_unit_l_s = sul.street_unit_l_s
--
下方:我从中提取的地址历史记录 View
CREATE OR REPLACE FORCE VIEW a_wpd_address_history (wpd_address_history_s,
wpd_plan_check_s,
street_num,
street_frac,
street_prefix,
street_name,
street_type_l_s,
street_suffix,
street_unit_l_s,
street_unit_num,
cross_streets,
city,
state_l_s,
state,
zip,
zip_ext,
zip_with_ext,
LOCATION,
apn_num,
river_desc,
first_inserted
)
AS
SELECT DISTINCT a.wpd_address_history_s, a.wpd_plan_check_s, a.street_num,
a.street_frac, a.street_prefix, a.street_name,
a.street_type_l_s, a.street_suffix, a.street_unit_l_s,
a.street_unit_num, a.cross_streets, a.city, a.state_l_s,
s.state, a.zip, a.zip_ext,
a.zip
|| NVL2 (a.zip_ext, '-' || a.zip_ext, '') AS zip_with_ext,
LTRIM (a.street_num || ' ')
|| LTRIM (NVL (a.street_frac, ' ') || ' ')
|| LTRIM (NVL (a.street_prefix, ' ') || ' ')
|| LTRIM (NVL (a.street_name, ' ') || ' ')
|| LTRIM (NVL (stl.street_type_desc, ' ') || ' ')
|| LTRIM (NVL (a.street_suffix, ' ') || ' ') AS LOCATION,
a.apn_num, r.river_desc, first_inserted
FROM wpd_address_history a LEFT OUTER JOIN street_type_l stl
ON a.street_type_l_s = stl.street_type_l_s
LEFT OUTER JOIN street_unit_l sul
ON a.street_unit_l_s = sul.street_unit_l_s
LEFT OUTER JOIN state_l s ON a.state_l_s = s.state_l_s
LEFT OUTER JOIN river_l r ON a.river_l_s = r.river_l_s
最佳答案
最常见的解决方案是这样的
SELECT
awa.wpd_address_history_s,
wpc.wpd_plan_check_s,
wpc.pcis_display,
awa.street_num,
awa.street_frac,
awa.street_prefix,
awa.street_name,
awa.street_type_l_s,
awa.street_suffix,
awa.street_unit_l_s,
awa.street_unit_num,
awa.cross_streets,
awa.city,
awa.state,
awa.state_l_s,
awa.zip,
awa.zip_ext,
awa.zip_with_ext,
wf.ind_id,
wpc.wpd_status_l_s,
wsl.wpd_status_desc,
awa.location as LOCATION,
wc.contact_name
FROM
wpd_plan_check wpc
LEFT OUTER JOIN a_wpd_address_history awa ON wpc.wpd_plan_check_s = awa.wpd_plan_check_s
LEFT OUTER JOIN wpd_contact wc ON wpc.wpd_plan_check_s = wc.wpd_plan_check_s
LEFT OUTER JOIN wpd_facility wf ON wpc.wpd_plan_check_s = wf.wpd_plan_check_s
LEFT OUTER JOIN wpd_status_l wsl ON wpc.wpd_status_l_s = wsl.wpd_status_l_s
LEFT OUTER JOIN street_type_l stl ON awa.street_type_l_s = stl.street_type_l_s
LEFT OUTER JOIN street_unit_l sul ON awa.street_unit_l_s = sul.street_unit_l_s
WHERE awa.first_inserted = (SELECT MAX(awa2.first_inserted)
FROM a_wpd_address_history awa2
WHERE awa.wpd_plan_check_s = awa2.wpd_plan_check_s)
但是,使用分析函数执行此类操作可能效率更高,这样您只需点击一次 View 。
WITH awa AS (
SELECT awa_inner.*,
RANK() OVER (PARTITION BY wpd_plan_check_s ORDER BY first_inserted DESC) rnk
FROM a_wpd_address_history awa_inner
)
SELECT
awa.wpd_address_history_s,
wpc.wpd_plan_check_s,
wpc.pcis_display,
awa.street_num,
awa.street_frac,
awa.street_prefix,
awa.street_name,
awa.street_type_l_s,
awa.street_suffix,
awa.street_unit_l_s,
awa.street_unit_num,
awa.cross_streets,
awa.city,
awa.state,
awa.state_l_s,
awa.zip,
awa.zip_ext,
awa.zip_with_ext,
wf.ind_id,
wpc.wpd_status_l_s,
wsl.wpd_status_desc,
awa.location as LOCATION,
wc.contact_name
FROM
wpd_plan_check wpc
LEFT OUTER JOIN awa ON wpc.wpd_plan_check_s = awa.wpd_plan_check_s
LEFT OUTER JOIN wpd_contact wc ON wpc.wpd_plan_check_s = wc.wpd_plan_check_s
LEFT OUTER JOIN wpd_facility wf ON wpc.wpd_plan_check_s = wf.wpd_plan_check_s
LEFT OUTER JOIN wpd_status_l wsl ON wpc.wpd_status_l_s = wsl.wpd_status_l_s
LEFT OUTER JOIN street_type_l stl ON awa.street_type_l_s = stl.street_type_l_s
LEFT OUTER JOIN street_unit_l sul ON awa.street_unit_l_s = sul.street_unit_l_s
WHERE awa.rnk = 1
关于SQL 语句 - 查询一组具有最近日期的记录,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/4870333/