Select item type and its base type in SQL Server? - sql

Question

I have a simple table :
DECLARE #t TABLE(item INT, itemType INT )
insert INTO #t SELECT 1000,0
insert INTO #t SELECT 1000,3
insert INTO #t SELECT 1000,5
insert INTO #t SELECT 1000,6
insert INTO #t SELECT 2000,0
insert INTO #t SELECT 2000,3
insert INTO #t SELECT 2000,5
insert INTO #t SELECT 2000,6
insert INTO #t SELECT 3000,0
insert INTO #t SELECT 3000,10
insert INTO #t SELECT 4000,11
I want to select all items where itemtype = 3 but if there is a row , provide also its base itemtype (if it exists) which is itemType = 0.
For example :
for itemType = 3
1000,0 should be provided --why ? because table also has 1000 + itemType 0
1000,3 should be provided --why ? because we looked for itemType=3
2000,0 should be provided --why ? because table has found 2000,3 and this 2000 also has itemType=0
2000,3 should be provided --why ? because we looked for itemType=3
for itemType = 10
3000,0 should be provided --why ? because table has found 3000,10 and this 3000 also has itemType=0
3000,10 should be provided --why ? because we looked for itemType=10
for itemType = 11
4000,11 should be provided --why ? because we looked for itemType=11 ( notice , there isn't itemType 0 , so only itself).
I started doing :
;with cte as(
SELECT * FROM #t
)
select * from cte where itemType=3
In summary, if the itemType is found, provide itself + its zero type (if exists), and also for his siblings ( sample(#1) )
But I can't do union here cause CTE is not recognized there... rubbish. it is possible.
How can I solve it ?
SQL ONLINE

Answer 1

To avoid evaluating the itemType = 3 query twice you can self outer join then use CROSS APPLY ... VALUES to UNPIVOT
DECLARE #itemType INT = 3;
WITH T(item1, itemType1, item2, itemType2 )
AS (SELECT *
FROM #t T1
LEFT JOIN #t T2
ON T1.item = T2.item
AND T2.itemType = 0
AND T1.itemType <> 0
WHERE T1.itemType = #itemType)
SELECT item,
itemType
FROM T
CROSS APPLY ( VALUES (item1, itemType1),
(item2, itemType2) ) v(item, itemType)
WHERE item IS NOT NULL
SQL Fiddle
Execution Plans

Answer 2

DECLARE #findtype INT = 3;
WITH results AS
(
SELECT t.item, #findtype
FROM #t t
WHERE t.itemType = #findtype
UNION ALL
SELECT t.item, 0
FROM #t t
INNER JOIN results r on r.item = t.item
WHERE t.itemType = 0
)
SELECT *
FROM results;

Answer 3

WITH recordList
AS
(
SELECT item, itemType
FROM SampleTable
WHERE itemType = 11 -- change here
)
SELECT item, itemType FROM recordList
UNION
SELECT a.item, a.itemType
FROM SampleTable a
INNER JOIN recordList b
ON a.item = b.item
WHERE a.itemtype = 0
SQLFiddle Demo
SQLFiddle Demo (using IN clause for multiple values)