Get index of row within a group? - tsql

Question

I have two tables:
Unit:
UnitId int PK
Title varchar
UnitOption:
UnitOptionId int PK
UnitId int FK
Title varchar
Quote:
QuoteId int PK
UnitOptionId int FK
Title varchar
I want to create a scalar UDF that takes a QuoteId param and returns a varchar that contains the following description (pseudu):
Quote.Title + '-' + Unit.Title + '-' + Unit.UnitId +
/* Here is where my question is:
If there are more than 1 UnitOption under this Unit, then
return '-' + the UnitOption number under this Unit
(i.e.) if under this Unit, there are 3 UnitOption with IDs 13, 17, 55
under the unit, and the current Quote.UnitOptionId is the 17 one,
it should return 2.
Which means I want to retrieve an ID of this row in the group.
Else
return ''
*/

Answer 1

If you're using SQL 2005 or later and I've interpreted your question correctly, you should be able to adapt the following into your function.
WITH [UnitExt] AS
(
SELECT
[Unit].[UnitId],
[Unit].[Title],
COUNT(*) AS [Count]
FROM [Unit]
INNER JOIN [UnitOption] ON [UnitOption].[UnitId] = [Unit].[UnitId]
GROUP BY
[Unit].[UnitId],
[Unit].[Title]
)
SELECT
[Quote].[Title] + '-' + [UnitExt].[Title] + '-' + [UnitExt].[UnitId] +
CASE
WHEN [UnitExt].[Count] > 1 THEN '-' +
CAST([UnitOption].[UnitOptionId] AS varchar(max))
ELSE ''
END
FROM [Quote]
INNER JOIN [UnitOption] ON [UnitOption].[UnitOptionId] =
[Quote].[UnitOptionId]
INNER JOIN [UnitExt] ON [UnitExt].[UnitId] = [UnitOption].[UnitId]
WHERE [Quote].[QuoteId] = #QuoteId

Answer 2

Something like this should do it.
SELECT DISTINCT Quote.Title +
' - ' + Unit.Title +
' - ' + Unit.UnitId +
CASE
WHEN COUNT(*) OVER(PARTITION BY Quote.Id) > 0
THEN
' - ' + CAST(ROW_NUMBER() OVER (PARTITION BY Quote.Id ORDER BY Quote.UnitOptionId) AS varchar)
ELSE
''
END
FROM Quote
JOIN UnitOption ON UnitOption.Id = Quote.UnitOptionId
JOIN Unit ON Unit.Id = UnitOption.UnitId
WHERE Quote.Id = #QuoteId

Answer 3

CREATE FUNCTION ufnGetDescription
(#QuoteID INT)
RETURNS VARCHAR(MAX)
AS
BEGIN
DECLARE #RetVal VARCHAR(MAX);
WITH CurRow
AS (SELECT quote.title + '- ' + unit.title AS start,
u.unitid,
quoteid,
uo.unitoptionid
FROM quote
INNER JOIN unitoption uo
ON quote.unitoptionid = uo.unitoptionid
INNER JOIN unit
ON uo.unitid = unit.unitid
WHERE quote.quoteid = #QuoteID),
AllUnits
AS (SELECT u.unitid,
uo.unitoptionid,
Row_number()
OVER(PARTITION BY u.unitid ORDER BY uo.unitoptionid) AS NUMBER,
Count(* )
OVER(PARTITION BY u.unitid ) AS cntUnits
FROM unit
INNER JOIN unionoption uo
ON unit.unitid = uo.unitid
WHERE u.unitid IN (SELECT unitid
FROM CurRow))
SELECT #RetVal = CASE
WHEN a.cntUnits = 1 THEN ''
ELSE r.start + '-' + Cast(NUMBER AS VARCHAR(max))
END
FROM AllUnits a
INNER JOIN CurRow r
ON a.unitoptionid = r.unitoptionid
RETURN #RetVal
END