Sql 寻找两个日期之间覆盖的员工的更有效方法

我需要检索一份员工列表，并为每位员工提供一份他们在给定年份积极参加福利保险的月份列表。有一个包含职务数据的表和一个包含福利信息的表。还有一个交付日期表，列出了2007-2018年的每个日期，并显示了每个日期的月份、月份和日历年

我现在编写查询的方式是：查找dates表中的所有日期，1在提示年份的01/01和12/31之间，或当前日期，以较早的日期为准，2在员工在福利表中处于活动状态期间。对于每个日期，我还希望从jobs表中获取deptid，并从benefit表中获取截至该日期的福利计划。然后我做了一个不同的，只显示每个员工的月份和日历年

这是可行的，但当我试图为有很多人的部门做这件事时，问题就来了。我相信它需要很长时间才能运行，因为它为每个员工检索多达365行，然后只显示其中的12行，因为它只需要几个月的时间。我觉得有更好的方法可以做到这一点，我只是想不出它是什么

下面是一些我正在使用的表的简化示例：

日期表 工作表 A=有效；I=不活动

EMPLID     EFFDT         DEPTID           HR_STATUS
00123      01-FEB-15     900              A
00123      30-JUN-15     900              I
00123      01-AUG-15     901              A

福利表 期望结果 获取上述结果的示例SQL 与其说检索每一个日期并检查它是否符合标准，我是否可以改变逻辑以获得相同的结果，而不必翻动这么多行？

是；通过使用LEAD分析函数，您可以计算jobs and benefits表中的下一个effdt，这使得在范围之间进行查询更加容易

比如：

with dates as (select trunc(sysdate, 'yyyy') - 1 + level the_date,
                      to_number(to_char(trunc(sysdate, 'yyyy') - 1 + level, 'mm')) monthofyear,
                      to_number(to_char(sysdate, 'yyyy')) calendar_year
               from   dual
               connect by level <= 365),
      jobs as (select 123 emplid, to_date('01/02/2015', 'dd/mm/yyyy') effdt, 900 deptid, 'A' hr_status from dual union all
               select 123 emplid, to_date('30/06/2015', 'dd/mm/yyyy') effdt, 900 deptid, 'I' hr_status from dual union all
               select 123 emplid, to_date('01/08/2015', 'dd/mm/yyyy') effdt, 901 deptid, 'A' hr_status from dual),
  benefits as (select 123 emplid, to_date('01/03/2015', 'dd/mm/yyyy') effdt, 'PPO' benefit_plan, 'A' status from dual union all
               select 123 emplid, to_date('31/07/2015', 'dd/mm/yyyy') effdt, null benefit_plan, 'I' status from dual union all
               select 123 emplid, to_date('01/09/2015', 'dd/mm/yyyy') effdt, 'HMO' benefit_plan, 'A' status from dual),
-- ********* end of mimicking your tables ********* --
         j as (select emplid,
                      effdt,
                      deptid,
                      hr_status,
                      lead(effdt, 1, sysdate) over (partition by emplid order by effdt) next_effdt
               from   jobs),
         b as (select emplid,
                      effdt,
                      benefit_plan,
                      status,
                      lead(effdt, 1, sysdate) over (partition by emplid order by effdt) next_effdt
               from   benefits)
select distinct j.emplid,
                d.calendar_year,
                d.monthofyear,
                j.deptid,
                b.benefit_plan
from   j
       inner join dates d on (d.the_date >= j.effdt and d.the_date < j.next_effdt)
       inner join b on (j.emplid = b.emplid)
where  d.the_date <= sysdate
and    d.the_date between to_date (:year_prompt || '01-01', 'YYYY-MM-DD')
                      and to_date (:year_prompt || '12-31', 'YYYY-MM-DD') -- if no index on d.the_date, maybe use trunc(the_date, 'yyyy') = :year_prompt
and    b.status = 'A'
and    d.the_date between b.effdt and b.next_effdt
order by 1, 4, 2, 3;

    EMPLID CALENDAR_YEAR MONTHOFYEAR     DEPTID BENEFIT_PLAN
---------- ------------- ----------- ---------- ------------
       123          2015           3        900 PPO         
       123          2015           4        900 PPO         
       123          2015           5        900 PPO         
       123          2015           6        900 PPO         
       123          2015           7        900 PPO         
       123          2015           9        901 HMO         
       123          2015          10        901 HMO         
       123          2015          11        901 HMO   

---

您正在交叉连接日期表和作业表。看起来是这样，但不是这样，这两个表之间存在基于最后一个谓词的连接条件。诡计多端，诡计多端！这个SQL对于创建日期表的子查询来说很有趣。我得把它留着，以备以后用。然而，它仍然在检索每个日期，并检查它是否符合标准。例如，如果从查询中删除distinct关键字，将返回219行。我的目标是防止SQL在这么多行中翻滚。有没有办法不使用distinct关键字就得到相同的结果；我本想检查清楚的部分，但忘了！明天我会再看一遍。谢谢你的帮助，这件事我一直很难弄清楚。我没有在问题中明确指出，尽管我可能应该说，我假设这可以在没有日期表的情况下完成。我想也许有办法查看福利表上的范围，并列出他们活跃的月份列表。但是，如果不使用dates表并在每一行上询问“此日期是否符合标准”问题，则可能无法执行此操作。完全可以避免使用dates表，尽管这有点复杂。在此期间，您可以对每个trunc日期的日期表使用行数分析函数，然后将其与jobs and benefits表连接，其中=1，尽管您也必须将开始/结束日期trunc到月初。感谢您花时间处理此问题。这并不完全是我想要的，但听起来我想要的可能真的不可能。所以，我会继续，把你的答案记下来。谢谢

EMPLID     EFFDT         BENEFIT_PLAN     STATUS
00123      01-MAR-15     PPO              A
00123      31-JUL-15                      I
00123      01-SEP-15     HMO              A

EMPLID     CALENDAR_YEAR MONTHOFYEAR      DEPTID         BENEFIT_PLAN
00123      2015          3                900            PPO
00123      2015          4                900            PPO
00123      2015          5                900            PPO
00123      2015          6                900            PPO
00123      2015          7                900            PPO
00123      2015          9                901            HMO
00123      2015          10               901            HMO
00123      2015          11               901            HMO
^ (shows November row even though employee was only covered for part of this month)

SELECT DISTINCT J.EMPLID, D.CALENDAR_YEAR, D.MONTHOFYEAR, J.DEPTID, B.BENEFIT_PLAN
FROM DATES D, 
     JOBS J 
     JOIN 
     BENEFITS B 
     ON J.EMPLID = B.EMPLID
WHERE D.THE_DATE <= SYSDATE
AND D.THE_DATE BETWEEN 
        TO_DATE(:YEAR_PROMPT || '01-01', 'YYYY-MM-DD') 
        AND 
        TO_DATE(:YEAR_PROMPT || '12-31', 'YYYY-MM-DD')
AND B.STATUS = 'A'
AND D.THE_DATE BETWEEN 
        B.EFFDT 
        AND 
        NVL(SELECT MIN(B_ED.EFFDT) 
            FROM BENEFITS B_ED
            WHERE B_ED.EMPLID = B.EMPLID
            AND B_ED.EFFDT > B.EFFDT
        , SYSDATE)
AND J.EFFDT = (SELECT MAX(J_ED.EFFDT)
               FROM JOBS J_ED
               WHERE J_ED.EMPLID = J.EMPLID
               AND J_ED.EFFDT <= D.THE_DATE)

with dates as (select trunc(sysdate, 'yyyy') - 1 + level the_date,
                      to_number(to_char(trunc(sysdate, 'yyyy') - 1 + level, 'mm')) monthofyear,
                      to_number(to_char(sysdate, 'yyyy')) calendar_year
               from   dual
               connect by level <= 365),
      jobs as (select 123 emplid, to_date('01/02/2015', 'dd/mm/yyyy') effdt, 900 deptid, 'A' hr_status from dual union all
               select 123 emplid, to_date('30/06/2015', 'dd/mm/yyyy') effdt, 900 deptid, 'I' hr_status from dual union all
               select 123 emplid, to_date('01/08/2015', 'dd/mm/yyyy') effdt, 901 deptid, 'A' hr_status from dual),
  benefits as (select 123 emplid, to_date('01/03/2015', 'dd/mm/yyyy') effdt, 'PPO' benefit_plan, 'A' status from dual union all
               select 123 emplid, to_date('31/07/2015', 'dd/mm/yyyy') effdt, null benefit_plan, 'I' status from dual union all
               select 123 emplid, to_date('01/09/2015', 'dd/mm/yyyy') effdt, 'HMO' benefit_plan, 'A' status from dual),
-- ********* end of mimicking your tables ********* --
         j as (select emplid,
                      effdt,
                      deptid,
                      hr_status,
                      lead(effdt, 1, sysdate) over (partition by emplid order by effdt) next_effdt
               from   jobs),
         b as (select emplid,
                      effdt,
                      benefit_plan,
                      status,
                      lead(effdt, 1, sysdate) over (partition by emplid order by effdt) next_effdt
               from   benefits)
select distinct j.emplid,
                d.calendar_year,
                d.monthofyear,
                j.deptid,
                b.benefit_plan
from   j
       inner join dates d on (d.the_date >= j.effdt and d.the_date < j.next_effdt)
       inner join b on (j.emplid = b.emplid)
where  d.the_date <= sysdate
and    d.the_date between to_date (:year_prompt || '01-01', 'YYYY-MM-DD')
                      and to_date (:year_prompt || '12-31', 'YYYY-MM-DD') -- if no index on d.the_date, maybe use trunc(the_date, 'yyyy') = :year_prompt
and    b.status = 'A'
and    d.the_date between b.effdt and b.next_effdt
order by 1, 4, 2, 3;

    EMPLID CALENDAR_YEAR MONTHOFYEAR     DEPTID BENEFIT_PLAN
---------- ------------- ----------- ---------- ------------
       123          2015           3        900 PPO         
       123          2015           4        900 PPO         
       123          2015           5        900 PPO         
       123          2015           6        900 PPO         
       123          2015           7        900 PPO         
       123          2015           9        901 HMO         
       123          2015          10        901 HMO         
       123          2015          11        901 HMO   

with dates as (select add_months(to_date(:year_prompt || '-01-01', 'YYYY-MM-DD'), - 1 + level) the_date,
                      level monthofyear,
                      :year_prompt calendar_year -- assuming this is a number
               from   dual
               connect by level <= 12),
      jobs as (select 123 emplid, to_date('01/02/2015', 'dd/mm/yyyy') effdt, 900 deptid, 'A' hr_status from dual union all
               select 123 emplid, to_date('15/06/2015', 'dd/mm/yyyy') effdt, 900 deptid, 'I' hr_status from dual union all
               select 123 emplid, to_date('26/06/2015', 'dd/mm/yyyy') effdt, 900 deptid, 'A' hr_status from dual union all
               select 123 emplid, to_date('01/08/2015', 'dd/mm/yyyy') effdt, 901 deptid, 'A' hr_status from dual),
  benefits as (select 123 emplid, to_date('01/03/2015', 'dd/mm/yyyy') effdt, 'PPO' benefit_plan, 'A' status from dual union all
               select 123 emplid, to_date('31/07/2015', 'dd/mm/yyyy') effdt, null benefit_plan, 'I' status from dual union all
               select 123 emplid, to_date('01/09/2015', 'dd/mm/yyyy') effdt, 'HMO' benefit_plan, 'A' status from dual),
-- ********* end of mimicking your tables ********* --
         j as (select emplid,
                      trunc(effdt, 'mm') effdt,
                      deptid,
                      hr_status,
                      trunc(coalesce(lead(effdt) over (partition by emplid order by effdt) -1, sysdate), 'mm') end_effdt
                        -- subtracting 1 from the lead(effdt) since here since the original sql had d.the_date < j.next_effdt and we need
                        -- to take into account when the next_effdt is the first of the month; we want the previous month to be displayed
               from   jobs),
         b as (select emplid,
                      trunc(effdt, 'mm') effdt,
                      benefit_plan,
                      status,
                      trunc(lead(effdt, 1, sysdate) over (partition by emplid order by effdt), 'mm') end_effdt
               from   benefits)
select distinct j.emplid,
                d.calendar_year,
                d.monthofyear,
                j.deptid,
                b.benefit_plan
from   j
       inner join dates d on (d.the_date between j.effdt and j.end_effdt)
       inner join b on (j.emplid = b.emplid)
where  d.the_date <= sysdate
and    b.status = 'A'
and    d.the_date between b.effdt and b.end_effdt
order by 1, 4, 2, 3;

    EMPLID CALENDAR_YEAR MONTHOFYEAR     DEPTID BENEFIT_PLAN                    
---------- ------------- ----------- ---------- --------------------------------
       123 2015                    3        900 PPO                             
       123 2015                    4        900 PPO                             
       123 2015                    5        900 PPO                             
       123 2015                    6        900 PPO                             
       123 2015                    6        900 PPO                             
       123 2015                    7        900 PPO                             
       123 2015                    9        901 HMO                             
       123 2015                   10        901 HMO                             
       123 2015                   11        901 HMO