T-SQL nested cursor with parameter - sql-server

Question

I have two cursors, I want to loop through first one, and use its values as parameters for the second cursor and then do some processing. I know how to do this in PL-SQL, but T-SQL puzzles me.
I have gotten so far. For some reason the nested cursor does not print anything.
DECLARE #period DATE
DECLARE #table_type VARCHAR(2)
DECLARE #clmn_clr VARCHAR(100)
DECLARE #clmn_per VARCHAR(100)
DECLARE #period_num INT
DECLARE #period_date DATE
DECLARE #table_type2 VARCHAR(2)
DECLARE c_table CURSOR FOR SELECT period,
table_type
FROM #period_table
DECLARE c_period CURSOR LOCAL FAST_FORWARD FOR SELECT clmn_clr,
clmn_per,
period_num,
period_date,
table_type
FROM #column_period
WHERE table_type = #table_type
OPEN c_table
FETCH NEXT FROM c_table
INTO #period, #table_type
WHILE ##FETCH_STATUS = 0
BEGIN
print #period
print #table_type
print '------------'
FETCH NEXT FROM c_table
INTO #period, #table_type
--Nested cursor
OPEN c_period
FETCH NEXT FROM c_period
INTO #clmn_clr, #clmn_per, #period_num, #period_date, #table_type2
BEGIN
print #clmn_clr
print #clmn_per
print #period_num
print #period_date
print #table_type2
FETCH NEXT FROM c_period
INTO #clmn_clr, #clmn_per, #period_num, #period_date, #table_type2
END
CLOSE c_period
DEALLOCATE c_period
END
CLOSE c_table
DEALLOCATE c_table
It does print the first line from cursor c_table but that is all.
Also, any comments for how to do this in T-SQL better are very welcomed.

Answer 1

There is no need in nesting, here is the only cursor that can do everything:
DECLARE c_period CURSOR LOCAL FAST_FORWARD FOR
SELECT p.period,
c.clmn_clr,
c.clmn_per,
c.period_num,
c.period_date,
c.table_type
FROM #period_table p
INNER JOIN #column_period c
ON c.table_type = p.table_type
ORDER BY p.table_type
I never tested it but id does not seem to me that MSSQL allows something like "dynamic parameter binding" for cursor. Since you opened it - it's done. It only can react on data modifications if appripriate options applied.
You may reopen cursor if you still need nesting for any purpose. Fetch #table_type from outer cursor, then DECLARE ... OPEN nested cursor.
Also note that strings to print (if this is your real subject) can be obtained with single select, withot any cursors (search "string aggregation" for mssql).

Answer 2

Here is working solution I have found - I only moved the nested cursor inside.
DECLARE #period DATE
DECLARE #table_type VARCHAR(2)
DECLARE #clmn_clr VARCHAR(100)
DECLARE #clmn_per VARCHAR(100)
DECLARE #period_num INT
DECLARE #period_date DATE
DECLARE #table_type2 VARCHAR(2)
DECLARE c_table CURSOR FOR SELECT period,
table_type
FROM #period_table
--Fetch first row
OPEN c_table
FETCH NEXT FROM c_table
INTO #period, #table_type
--Loop starts here, until it is empty
WHILE ##FETCH_STATUS = 0
BEGIN
print #period
print #table_type
print '----------'
--Nested cursor
DECLARE c_period CURSOR LOCAL FAST_FORWARD FOR SELECT clmn_clr,
clmn_per,
period_num,
period_date,
table_type
FROM #column_period
WHERE table_type = #table_type
OPEN c_period
FETCH NEXT FROM c_period
INTO #clmn_clr, #clmn_per, #period_num, #period_date, #table_type2
WHILE ##FETCH_STATUS = 0
BEGIN
print #clmn_clr
print #clmn_per
print #period_num
print #period_date
print #table_type2
FETCH NEXT FROM c_period
INTO #clmn_clr, #clmn_per, #period_num, #period_date, #table_type2
END
CLOSE c_period
DEALLOCATE c_period
FETCH NEXT FROM c_table
INTO #period, #table_type
END
CLOSE c_table
DEALLOCATE c_table