带有 CTE 的 MERGE 语句中的 OPTION (MAXRECURSION X) 不起作用？

Question

我有以下 CTE（Microsoft SQL Server 2017）按预期工作：

WITH DATE_CTE (Datum)
as
(
    SELECT DATEFROMPARTS(1970, 1, 1)
    UNION ALL
    SELECT DATEADD(Day, 1, DATE_CTE.Datum) FROM DATE_CTE WHERE YEAR(DATE_CTE.Datum) < 2100 
) 
SELECT DATE_CTE.Datum, 
        YEAR(DATE_CTE.Datum) as [Year], 
        MONTH(DATE_CTE.Datum) as [Month], 
        DATEPART(ISO_WEEK, DATE_CTE.Datum) as IsoWeek, 
        CAST(YEAR(DATE_CTE.Datum) AS VARCHAR(4)) + IIF(MONTH(DATE_CTE.Datum) < 10, '0' + CAST(MONTH(DATE_CTE.Datum) AS VARCHAR(1)), CAST(MONTH(DATE_CTE.Datum) AS VARCHAR(2))) as YearMonth, 
        -1 as SelID,  
        CASE WHEN MONTH(DATE_CTE.Datum) = 1 AND DATEPART(ISO_WEEK, DATE_CTE.Datum) >= 52 THEN YEAR(DATE_CTE.Datum)-1 WHEN MONTH(DATE_CTE.Datum) = 12 AND DATEPART(ISO_WEEK, DATE_CTE.Datum) = 1 THEN YEAR(DATE_CTE.Datum)+1 ELSE YEAR(DATE_CTE.Datum) END as WeekYear
FROM DATE_CTE OPTION (MAXRECURSION 0)

这将return以下数据（从 1970 到 2100 -> 47483 数据行）：

    Date       Year        Month       IsoWeek     YearMonth SelID       WeekYear
    ---------- ----------- ----------- ----------- --------- ----------- -----------
    1970-01-01 1970        1           1           197001    -1          1970
    1970-01-02 1970        1           1           197001    -1          1970
    1970-01-03 1970        1           1           197001    -1          1970
    1970-01-04 1970        1           1           197001    -1          1970
    1970-01-05 1970        1           2           197001    -1          1970
    1970-01-06 1970        1           2           197001    -1          1970
    1970-01-07 1970        1           2           197001    -1          1970
    1970-01-08 1970        1           2           197001    -1          1970
    1970-01-09 1970        1           2           197001    -1          1970
    1970-01-10 1970        1           2           197001    -1          1970
    ...

现在我想将数据保存在特定的 table 中，其中可能已经有一些数据（甚至更糟：可能有一些额外的字段）。所以我的想法是使用这样的合并语句：

WITH DATE_CTE (Datum)
as
(
    SELECT DATEFROMPARTS(1970, 1, 1)
    UNION ALL
    SELECT DATEADD(Day, 1, DATE_CTE.Datum) FROM DATE_CTE WHERE YEAR(DATE_CTE.Datum) < 2100 
) 
MERGE INTO SYS_LIST_DATEHLP AS Target  
USING (
        SELECT 
                DATE_CTE.Datum, 
                YEAR(DATE_CTE.Datum), 
                MONTH(DATE_CTE.Datum), 
                DATEPART(ISO_WEEK, DATE_CTE.Datum), 
                CAST(YEAR(DATE_CTE.Datum) AS VARCHAR(4)) + IIF(MONTH(DATE_CTE.Datum) < 10, '0' + CAST(MONTH(DATE_CTE.Datum) AS VARCHAR(1)), 
                CAST(MONTH(DATE_CTE.Datum) AS VARCHAR(2))), 
                -1, 
                CASE WHEN MONTH(DATE_CTE.Datum) = 1 AND DATEPART(ISO_WEEK, DATE_CTE.Datum) >= 52 THEN YEAR(DATE_CTE.Datum)-1 WHEN MONTH(DATE_CTE.Datum) = 12 AND DATEPART(ISO_WEEK, DATE_CTE.Datum) = 1 THEN YEAR(DATE_CTE.Datum)+1 ELSE YEAR(DATE_CTE.Datum) END
        FROM DATE_CTE OPTION (MAXRECURSION 0)
       )  
       AS Source (SYS_DATE, SYS_YEAR, SYS_MONTH, [WEEK], KAPMONAT, SEL_ID, WEEKYEAR)  
    ON Target.SYS_DATE = Source.SYS_DATE  
WHEN MATCHED THEN  
    UPDATE SET SYS_YEAR = Source.SYS_YEAR, SYS_MONTH = Source.SYS_MONTH, [WEEK] = Source.[WEEK], KAPMONAT = Source.KAPMONAT, SEL_ID = Source.SEL_ID, WEEKYEAR = Source.WEEKYEAR
WHEN NOT MATCHED BY TARGET THEN  
    INSERT (SYS_DATE, SYS_YEAR, SYS_MONTH, [WEEK], KAPMONAT, SEL_ID, WEEKYEAR)
    VALUES (Source.SYS_DATE, Source.SYS_YEAR, Source.SYS_MONTH, Source.[WEEK], Source.KAPMONAT, Source.SEL_ID, Source.WEEKYEAR);

但这总是失败并出现以下错误：

Incorrect syntax near the keyword 'OPTION'.

遗漏 OPTION (MAXRECURSION 0) 不是一个选项，因为 CTE 进行了 100 多次递归，然后 SQL 只是响应：

The statement terminated. The maximum recursion 100 has been exhausted before statement completion.

我必须在哪里设置OPTION (MAXRECURSION 0)？这有可能吗？遗憾的是，我没有在 Microsoft 文档中找到任何关于此 "special" 案例的提及。

Answer 1

您可以使用具有 CTE 结构的 table 变量来存储稍后将在 merge 语句中使用的结果：

declare @tmp table (
                        [Datum]     date, 
                        [Year]      int, 
                        [Month]     int,
                        [IsoWeek]   int, 
                        [YearMonth] int, 
                        [SelID]     int, 
                        [WeekYear]  int
                    )

然后您可以通过 MAXRECURSION 0 将结果写入 table 变量来执行 CTE：

WITH DATE_CTE (Datum)
as
(
    SELECT DATEFROMPARTS(1970, 1, 1)
    UNION ALL
    SELECT DATEADD(Day, 1, DATE_CTE.Datum) FROM DATE_CTE WHERE YEAR(DATE_CTE.Datum) < 2100 
) 
insert into @tmp
SELECT DATE_CTE.Datum, 
        YEAR(DATE_CTE.Datum) as [Year], 
        MONTH(DATE_CTE.Datum) as [Month], 
        DATEPART(ISO_WEEK, DATE_CTE.Datum) as IsoWeek, 
        CAST(YEAR(DATE_CTE.Datum) AS VARCHAR(4)) + IIF(MONTH(DATE_CTE.Datum) < 10, '0' + CAST(MONTH(DATE_CTE.Datum) AS VARCHAR(1)), CAST(MONTH(DATE_CTE.Datum) AS VARCHAR(2))) as YearMonth, 
        -1 as SelID,  
        CASE WHEN MONTH(DATE_CTE.Datum) = 1 AND DATEPART(ISO_WEEK, DATE_CTE.Datum) >= 52 THEN YEAR(DATE_CTE.Datum)-1 WHEN MONTH(DATE_CTE.Datum) = 12 AND DATEPART(ISO_WEEK, DATE_CTE.Datum) = 1 THEN YEAR(DATE_CTE.Datum)+1 ELSE YEAR(DATE_CTE.Datum) END as WeekYear
FROM DATE_CTE OPTION (MAXRECURSION 0)

现在您应该可以将 table SYS_LIST_DATEHLP 与 table 变量合并 @tmp:

MERGE INTO SYS_LIST_DATEHLP AS Target  
USING (
        SELECT 
             [Datum]     
            ,[Year]     
            ,[Month]    
            ,[IsoWeek]  
            ,[YearMonth]
            ,[SelID]    
            ,[WeekYear] 
        FROM @tmp  
       )  
       AS Source (SYS_DATE, SYS_YEAR, SYS_MONTH, [WEEK], KAPMONAT, SEL_ID, WEEKYEAR)  
    ON Target.SYS_DATE = Source.SYS_DATE  
WHEN MATCHED THEN  
    UPDATE SET SYS_YEAR = Source.SYS_YEAR, SYS_MONTH = Source.SYS_MONTH, [WEEK] = Source.[WEEK], KAPMONAT = Source.KAPMONAT, SEL_ID = Source.SEL_ID, WEEKYEAR = Source.WEEKYEAR
WHEN NOT MATCHED BY TARGET THEN  
    INSERT (SYS_DATE, SYS_YEAR, SYS_MONTH, [WEEK], KAPMONAT, SEL_ID, WEEKYEAR)
    VALUES (Source.SYS_DATE, Source.SYS_YEAR, Source.SYS_MONTH, Source.[WEEK], Source.KAPMONAT, Source.SEL_ID, Source.WEEKYEAR);

Answer 2

查询提示总是出现在查询的最后。所以只需将 OPTION (MAXRECURSION 0) 移到最后一个分号之前。

/* Rest of query omitted*/
WHEN NOT MATCHED BY TARGET THEN  
    INSERT (SYS_DATE, SYS_YEAR, SYS_MONTH, [WEEK], KAPMONAT, SEL_ID, WEEKYEAR)
    VALUES (Source.SYS_DATE, Source.SYS_YEAR, Source.SYS_MONTH, Source.[WEEK], Source.KAPMONAT, Source.SEL_ID, Source.WEEKYEAR)
     OPTION (MAXRECURSION 0)
    ;

带有 CTE 的 MERGE 语句中的 OPTION (MAXRECURSION X) 不起作用？

OPTION (MAXRECURSION X) in MERGE Statement with CTE not working?

sql

tsql

sql-server

sql-server-2017