Question

I have a TVF that returns two columns: ‘measure’ (a name) and ‘score’, a numeric score for that measure:

dbo.ScoringFunction(param1, param2, ..., paramN)
Measure   Score
-------   -----
measure1  10
measure2  5
...       ...
measureN  15

I’m running this function against a large number of rows that contain its parameters:

Name   Param1   Param2   ...   ParamN
----   ------   ------         ------
Daniel 12       5              6
etc.

I am trying to find a way to display the measures and their scores next to the parameters that determine those scores:

Name   Param1   Param2   ...   ParamN   measure1   measure2   ...   measureN
----   ------   ------         ------   --------   --------         --------
Daniel 12       5              6        10         5                15
etc.

So far I have tried using a pivot table, but it’s tricky since the data being pivoted is contained in a TVF rather than a static table. I’ve also tried using CROSS APPLY, but once I have the data (measures & scores), I’m still unable to pivot it into a nicely formatted row.

If anybody has any ideas, they would be much appreciated!

Answer 1

Without changing too much (hopefully), I would do the pivoting in the function, then use the function in CROSS APPLY and pull the columns. So if your function is something like this:

CREATE FUNCTION dbo.ScoringFunction (parameters)
RETURNS TABLE
RETURN (

SELECT Measure, Score
FROM …

)

then I would rewrite it like this:

CREATE FUNCTION dbo.ScoringFunction (parameters)
RETURNS TABLE
RETURN (

WITH originalSelect AS (
  SELECT Measure, Score
  FROM …
)
SELECT
  measure1,
  measure2,
  …
FROM originalSelect
PIVOT (
  MAX(Score) FOR Measure IN (measure1, measure2, …)
) p

)

and use it in the final query like this:

SELECT
  t.Name,
  t.param1,
  t.param2,
  …
  x.measure1,
  x.measure2,
  …
FROM atable t
CROSS APPLY dbo.ScoringFunction (t.param1, t.param2, …) x