根据每个 ID 的另一列的值查找一列的两个值

Question

我有一个 sqlite 数据库，其中 table 称为贷款。 table 示例数据在这里： Loan Table at sqlfiddle.com

此 table 包含以下栏目：

mainindex | brindx | YearMonth | EmpID | VarNo | Name | LastName | CodepayID | CodepaySH | Lval | Lint | Lrmn

现在，我需要一个查询来显示所需的结果，包含

[empid],[Codepayid],[Lval-1],[Lval-2],[Sum(Lint)],[Lrmn-1],[Lrmn-2],

有了这个条件：

[lVal-1] as Value of Lval Column of each Employee Correspond to their Lowest YearMonth
[lVal-2] as Value of Lval Column of each Employee Correspond to their Highest YearMonth
[Sum(Lint)] Sum of Lint Column for each Employee.
[Lrmn-1] as Value of Lrmn Column of each Emplyee Correspond to that Lowest YearMonth
[Lrmn-2] as Value of Lrmn Column of each Emplyee Correspond to that Highest YearMonth

例如：

select empid, Codepayid, Lval1, Lval2, Sum(Lint), Lrmn1, Lmrn2
   from Loan
   where CodepayID=649 and EmpID=12450400
   group by EmpID

结果：

员工 ID	CodepayID	Lval1	Lval2	总和（林特）	Lrmn1	Lrmn2
12450400	649	405480	405485	270320	337900	202740

Answer 1

要获得您想要的结果，首先您必须从每个员工的 table 中找到列 YearMonth 的最小值和最大值，并使用这些值来获取最小和最大 YearMonth 的相应 lval 和 lrmn。

您可以在存储过程中或在单个查询中执行此操作，具体取决于您的选择。以下是将提供您想要的输出的查询

SELECT l.empid, l.CodepayID,  min(a.lval1) as lval1, max(b.lval2) as lval2 ,sum(l.lint) as lint,min(a.lrmn1) as lrmn1,max(b.lrmn2) as lrmn2
   FROM    loan l inner join
       (    SELECT empid,CodepayID, lval lval1, Lrmn lrmn1
            FROM loan ln 
            WHERE YEARMonth = (SELECT MIN(YearMonth) 
                                FROM loan 
                                WHERE empid = ln.EmpID and CodepayID = ln.CodepayID  
                                group by empid,CodepayID)
        ) a on l.empid = a.EmpID and l.CodepayID = a.codepayid
   inner  join
        (   SELECT empid, CodepayID, YearMonth,lval lval2, Lrmn lrmn2
            FROM loan ln
            WHERE YEARMonth = (SELECT MAX(YearMonth) 
                                FROM loan 
                                WHERE empid = ln.EmpID and CodepayID = ln.CodepayID  
                                GROUP BY empid,CodepayID)
        ) b on l.empid = b.EmpID and l.CodepayID = b.codepayid
   GROUP BY l.EmpID,l.Codepayid

Answer 2

使用FIRST_VALUE()和SUM()window函数：

SELECT DISTINCT EmpID, CodepayID,
       FIRST_VALUE(Lval) OVER (PARTITION BY EmpID, CodepayID ORDER BY YearMonth) LVal1,
       FIRST_VALUE(Lval) OVER (PARTITION BY EmpID, CodepayID ORDER BY YearMonth DESC) LVal2,
       SUM(Lint) OVER (PARTITION BY EmpID, CodepayID) sum_Lint,
       FIRST_VALUE(Lrmn) OVER (PARTITION BY EmpID, CodepayID ORDER BY YearMonth) Lrmn1,
       FIRST_VALUE(Lrmn) OVER (PARTITION BY EmpID, CodepayID ORDER BY YearMonth DESC) Lrmn2
FROM loan

参见demo。

Answer 3

接受的答案不必要地过于复杂。即使您不想使用 window 函数，以下使用与接受的答案相同的逻辑，对数据库的工作要少得多，完全避免了相关的子查询...

SELECT
  l.empid,
  l.CodepayID,
  min(case when l.yearmonth = s.yearmonth_min then l.lval end) as lval1,
  max(case when l.yearmonth = s.yearmonth_max then l.lval end) as lval2, 
  sum(l.lint) as lint,
  min(case when l.yearmonth = s.yearmonth_min then l.lrmn end) as lrmn1,
  max(case when l.yearmonth = s.yearmonth_max then l.lrmn end) as lrmn2
FROM
  loan l
inner join
(
  select
    empid,
    CodepayID,
    min(yearmonth) as yearmonth_min,
    max(yearmonth) as yearmonth_max
  from
    loan
  group by
    empid,
    CodepayID
)
  s
    on  l.empid = s.empid
    and l.CodepayID = s.codepayid
group by
  l.EmpID, 
  l.Codepayid

根据每个 ID 的另一列的值查找一列的两个值

Find two values of one Column based on value of another column per ID

sql

sqlite

select

join

window-functions