将 SQL Server 游标转换为 Azure Synapse

Question

我有以下代码循环遍历具有唯一型号的表并创建一个新表，其中每个型号都包含基于年份和周数的行。我怎样才能翻译它，使它不使用光标？

DECLARE @current_model varchar(50);

--declare a cursor that iterates through model numbers in ItemInformation table
DECLARE model_cursor CURSOR FOR
SELECT model from ItemInformation
--start the cursor
OPEN model_cursor
--get the next (first value)
FETCH NEXT FROM model_cursor INTO @current_model;

DECLARE @year_counter SMALLINT;
DECLARE @week_counter TINYINT;

WHILE (@@FETCH_STATUS = 0) --fetch status returns the status of the last cursor, if 0 then there is a next value (FETCH statement was successful)
BEGIN
    SET @year_counter = 2019;
    WHILE (@year_counter <= Datepart(year, Getdate() - 1) + 2)
    BEGIN
        SET @week_counter = 1;
        WHILE (@week_counter <= 52)
        BEGIN
            INSERT INTO dbo.ModelCalendar(
                model,
                sales_year,
                sales_week
            )
            VALUES(
                @current_model,
                @year_counter,
                @week_counter
            )
            SET @week_counter = @week_counter + 1   
        END
        SET @year_counter = @year_counter + 1
    END
    FETCH NEXT FROM model_cursor INTO @current_model
END;
CLOSE model_cursor;
DEALLOCATE model_cursor;

如果 ItemInformation 包含下表：

model,invoice
a,4.99
b,9.99
c,1.99
d,8.99

那么预期的输出是：

model,sales_year,sales_week
A,2019,1
A,2019,2
A,2019,3
...
A,2019,52
A,2020,1
A,2020,2
A,2020,3
...
A,2020,51
A,2020,52
A,2020,53 (this is 53 because 2020 is leap year and has 53 weeks)
A,2021,1
A,2021,2
...
A,2022,1
A,2022,2
...
A,2022,52
B,2019,1
B,2019,2
...
D, 2022,52

Answer 1

使用 CTE，您可以获得所需范围内的所有周和年组合。然后加入你的数据表。

declare @Test table (model varchar(1), invoice varchar(4));

insert into @Test (model, invoice)
values
('a', '4.99'),
('b', '9.99'),
('c', '1.99'),
('d', '8.99');

with Week_CTE as (
  select 1 as WeekNo
  union all
  select 1 + WeekNo
  from Week_CTE 
  where WeekNo < 53
), Year_CTE as (
  select 2019 YearNo
  union all
  select 1 + YearNo
  from Year_CTE 
  where YearNo <= datepart(year, current_timestamp)
)
select T.model, yr.YearNo, wk.WeekNo 
from Week_CTE wk
cross join (
  select YearNo
    -- Find the last week of the year (52 or 53) -- might need to change the start day of the week for this to be correct
    , datepart(week, dateadd(day, -1, dateadd(year, 1, '01 Jan ' + convert(varchar(4),YearNo)))) LastWeek
  from Year_CTE yr
) yr
cross join (
  -- Assuming only a single row per model is required, and the invoice column can be ignored
  select model
  from @Test
  group by model
) T
where wk.WeekNo <= yr.LastWeek
order by yr.YearNo, wk.WeekNo;

正如您所建议的，使用递归 CTE 不是一种选择，您可以尝试使用不使用递归的 CTE：

with T(N) as (
  select X.N
  from (values (0),(0),(0),(0),(0),(0),(0),(0)) X(N)
), W(N) as (
  select top (53) row_number() over (order by @@version) as N
  from T T1
  cross join T T2
), Y(N) as (
  -- Upper limit on number of years
  select top (12) 2018 + row_number() over (order by @@version) AS N
  from T T1
  cross join T T2
)
select W.N as WeekNo, Y.N YearNo, T.model
from W
cross join (
  select N
    -- Find the last week of the year (52 or 53) -- might need to change the start day of the week for this to be correct
    , datepart(week, dateadd(day, -1, dateadd(year, 1, '01 Jan ' + convert(varchar(4),N)))) LastWeek
  from Y
) Y
cross join (
  -- Assuming only a single row per model is required, and the invoice column can be ignored
  select model
  from @Test
  group by model
) T
-- Filter to required number of years.
where Y.N <= datepart(year, current_timestamp) + 1
and W.N <= Y.LastWeek
order by Y.N, W.N, T.model;

注意：如果您将来使用此处所示的 DDL/DML 设置示例数据，您将极大地帮助尝试回答的人。

Answer 2

我创建了一个包含所有星期和年份的临时日历表。为了考虑闰年，我用了一年的最后 7 天，并得到了每一天的 ISO 周。要知道一年有多少周，我将这些值放入另一个临时表并取其最大值。 Azure Synapse 不支持在一个插入中包含多个值，因此它看起来比应有的长得多。我还必须将每个声明为变量，因为 Synapse 只能插入文字或变量。然后我交叉加入了我的 ItemInformation 表。

CREATE TABLE #temp_dates 
  ( 
     year SMALLINT, 
     week TINYINT 
  ); 

CREATE TABLE #temp_weeks 
  ( 
     week_num TINYINT 
  ); 

DECLARE @year_counter SMALLINT 

SET @year_counter = 2019 

DECLARE @week_counter TINYINT 

WHILE ( @year_counter <= Datepart(year, Getdate() - 1) + 2 ) 
  BEGIN 
      SET @week_counter = 1; 

      DECLARE @day_1 TINYINT 

      SET @day_1 = Datepart(isowk, Concat('12-25-', @year_counter)) 

      DECLARE @day_2 TINYINT 

      SET @day_2 = Datepart(isowk, Concat('12-26-', @year_counter)) 

      DECLARE @day_3 TINYINT 

      SET @day_3 = Datepart(isowk, Concat('12-27-', @year_counter)) 

      DECLARE @day_4 TINYINT 

      SET @day_4 = Datepart(isowk, Concat('12-28-', @year_counter)) 

      DECLARE @day_5 TINYINT 

      SET @day_5 = Datepart(isowk, Concat('12-29-', @year_counter)) 

      DECLARE @day_6 TINYINT 

      SET @day_6 = Datepart(isowk, Concat('12-30-', @year_counter)) 

      DECLARE @day_7 TINYINT 

      SET @day_7 = Datepart(isowk, Concat('12-31-', @year_counter)) 

      TRUNCATE TABLE #temp_weeks 

      INSERT INTO #temp_weeks 
                  (week_num) 
      VALUES      (@day_1) 

      INSERT INTO #temp_weeks 
                  (week_num) 
      VALUES      (@day_2) 

      INSERT INTO #temp_weeks 
                  (week_num) 
      VALUES      (@day_3) 

      INSERT INTO #temp_weeks 
                  (week_num) 
      VALUES      (@day_4) 

      INSERT INTO #temp_weeks 
                  (week_num) 
      VALUES      (@day_5) 

      INSERT INTO #temp_weeks 
                  (week_num) 
      VALUES      (@day_6) 

      INSERT INTO #temp_weeks 
                  (week_num) 
      VALUES      (@day_7) 

      DECLARE @max_week TINYINT 

      SET @max_week = (SELECT Max(week_num) 
                       FROM   #temp_weeks) 

      WHILE ( @week_counter <= @max_week ) 
        BEGIN 
            INSERT INTO #temp_dates 
                        (year, 
                         week) 
            VALUES     ( @year_counter, 
                         @week_counter ) 

            SET @week_counter = @week_counter + 1 
        END 

      SET @year_counter = @year_counter + 1 
  END 

DROP TABLE #temp_weeks; 

SELECT i.model, 
       d.year, 
       d.week 
FROM   dbo.iteminformation i 
       CROSS JOIN #temp_dates d 
ORDER  BY model, 
          year, 
          week
DROP TABLE #temp_dates 

Answer 3

我不希望看到可以找到固定解决方案的循环解决方案。所以这里有没有CTE、没有values 和没有row_number() 的Take II（表变量只是为了模拟您的数据，所以不是实际解决方案的一部分）：

declare @Test table (model varchar(1), invoice varchar(4));

insert into @Test (model, invoice)
values
('a', '4.99'),
('b', '9.99'),
('c', '1.99'),
('d', '8.99');

select Y.N + 2019 YearNumber, W.WeekNumber, T.Model
from (
  -- Cross join 5 * 10, then filter to 52/53 as required
  select W1.N * 10 + W2.N + 1 WeekNumber
  from (
    select 0 N
    union all select 1
    union all select 2
    union all select 3
    union all select 4
    union all select 5
  ) W1
  cross join (
    select 0 N
    union all select 1
    union all select 2
    union all select 3
    union all select 4
    union all select 5
    union all select 6
    union all select 7
    union all select 8
    union all select 9
  ) W2
) W
-- Cross join number of years required, just ensure its more than will ever be needed then filter back
cross join (
  select 0 N
  union all select 1
  union all select 2
  union all select 3
  union all select 4
  union all select 5
  union all select 6
  union all select 7
  union all select 8
  union all select 9
) Y
cross join (
  -- Assuming only a single row per model is required, and the invoice column can be ignored
  select model
  from @Test
  group by model
) T
-- Some filter to restrict the years
where Y.N <= 3
-- Some filter to restrict the weeks
and W.WeekNumber <= 53
order by YearNumber, WeekNumber;