Question

我有一个表，用于存储患者实验室测试结果。可以从白蛋白，钾，磷等多种测试中获得结果。来自每个类别的每位患者的第一读数据存储在名为#MetricFirstGroupReading的表中。

CREATE TABLE #MetricFirstGroupReading (Patient_Key INT, Metric_Group VARCHAR(100), 
                                       Observation_Date DATE)
ALTER TABLE #MetricFirstGroupReading 
ADD CONSTRAINT UQ_MetricFirst UNIQUE (Patient_Key, Metric_Group);

INSERT INTO #MetricFirstGroupReading
SELECT 1, 'Albumin', '2018-11-15' UNION
SELECT 1, 'Potassium', '2018-12-10' UNION
SELECT 2, 'Albumin', '2018-10-20' UNION
SELECT 2, 'Potassium', '2018-11-25'

现在，对于#MetricFirstGroupReading表中的每个记录，我需要将直到当前月份的所有月末日期填充到一个新表中。以下是查询于2018年12月运行时的预期结果。

我知道如何使用WHILE循环来做到这一点。如何在SQL Server 2016中使用基于集合的SQL查询来实现无循环操作？

Answer 1

以下工作。这是tsql: How to retrieve the last date of each month between given date range

中提出的想法的扩展

查询

CREATE TABLE #AllMonthEnds (MonthEndDate DATE)
DECLARE @Start datetime
DECLARE @End datetime

SELECT @Start = '2000-01-01'
SELECT @End = DATEADD(MONTH,1,GETDATE())
;With CTE as
(
    SELECT @Start  as Date,Case When DatePart(mm,@Start)<>DatePart(mm,@Start+1) then 1 else 0 end as [Last]
    UNION ALL
    SELECT Date+1,Case When DatePart(mm,Date+1)<>DatePart(mm,Date+2) then 1 else 0 end from CTE
    WHERE Date<@End
)

INSERT INTO #AllMonthEnds
SELECT [Date]
FROM CTE
WHERE [Last]=1   
OPTION ( MAXRECURSION 0 )



SELECT  T.Patient_Key, T.Metric_Group, T.Observation_Date AS First_Observation_Date,
        DATEDIFF(MONTh,Observation_Date, MonthEndDate) AS MonthDiff, 
         A.MonthEndDate AS IterationDate
FROM #AllMonthEnds A
INNER JOIN
(
    SELECT *, ROW_NUMBER() OVER(PARTITION BY Patient_Key, Metric_Group ORDER BY Observation_Date) AS RowVal
    FROM #MetricFirstGroupReading M
)T
    ON A.MonthEndDate >= T.Observation_Date
WHERE RowVal = 1
ORDER BY Patient_Key, Metric_Group, T.Observation_Date, A.MonthEndDate

Answer 2

怎么样：

    select MetricFirstGroupReading.*, datediff(month, MetricFirstGroupReading.Observation_Date, months.monthendval) monthdiff, months.* 
    into allmonths
    from
    (
    SELECT 1 patientid, 'Albumin' test, '2018-11-15' Observation_Date UNION
    SELECT 1 patientid, 'Potassium' test, '2018-12-10' Observation_Date UNION
    SELECT 2 patientid, 'Albumin' test, '2018-10-20' Observation_Date UNION
    SELECT 2 patientid, 'Potassium' test, '2018-11-25' Observation_Date) MetricFirstGroupReading 
join 
    (
    select '2018-10-31' monthendval union
    select '2018-11-30' monthendval union
    select '2018-12-31' monthendval 
    ) months on MetricFirstGroupReading.Observation_Date< months.monthendval

将第一个select联合替换为表，然后从第二个内部select中添加或删除月末。

Answer 3

考虑构建一个包含所有12个月结束日期的临时表，然后按日期范围加入主表。使用DateDiff表示月份差异：

CREATE TABLE #MonthEndDates (Month_End_Value DATE)

INSERT INTO #MonthEndDates
VALUES ('2018-01-31'),
       ('2018-02-28'),
       ('2018-03-31'),
       ('2018-04-30'),
       ('2018-05-31'),
       ('2018-04-30'),
       ('2018-06-30'),
       ('2018-07-31'),
       ('2018-08-31'),
       ('2018-09-30'),
       ('2018-10-31'),
       ('2018-11-30'),
       ('2018-12-31')

SELECT m.Patient_Key, m.Metric_Group, m.Observation_Date, 
       DateDiff(month, m.Observation_Date, d.Month_End_Value) AS Month_Diff, 
       d.Month_End_Value

FROM #MetricFirstGroupReading m
INNER JOIN #MonthEndDates d
  ON m.Observation_Date < d.Month_End_Value

GO

Rextester Demo

设置基于查询的替换循环以填充给定日期的所有记录的所有月末日期

3 个答案: