Translating SQL Server Cursor to Azure Synapse - sql-server

Question

I have the following code that loops through a table with unique model numbers and creates a new table that contains, for each model numbers, a row based on the year and week number. How can I translate this so it doesn't use a cursor?
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;
If ItemInformation contains the following table:
model,invoice
a,4.99
b,9.99
c,1.99
d,8.99
then the expected output is:
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

Using CTE's you can get all combinations of weeks and years within the range required. Then join your data table on.
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;
As you have advised that using a recursive CTE is not an option, you can try using a CTE without recursion:
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;
Note: If you setup your sample data in future with the DDL/DML as shown here you will greatly assist people attempting to answer.

Answer 2

I don't like to see a loop solution where a set solution can be found. So here goes Take II with no CTE, no values and no row_number() (the table variable is just to simulate your data so not part of the actual solution):
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;

Answer 3

I created a table to temporary calendar table containing all the weeks and years. To account for leap years, I took the last 7 days of a year and got the ISO week for each day. To know how many weeks are in a year, I put these values into another temp table and took the max value of it. Azure Synapse doesn't support multiple values in one insert so it looks a lot longer than it should be. I also have to declare each as variable since Synapse can only insert literal or variable. I then cross-joined with my ItemInformation table.
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