I have a stored procedure which creates a 2x2 table for an odds ratio. A rudimentary odds ratio table looks like:

EDIT - this query finally did finish and it did return the correct answer after two minutes and 32 separate calls to the function. I can't see why this is running recursively, any ideas, SO?

A - only records that satisfy both thing 1 and thing 2 go here
B - only records that satisfy thing 1 (people with thing 2 CANNOT go here)
C - only records that satisfy thing 2 (people with thing 1 CANNOT go here)
D - people with thing 1 OR thing 2 cannot go here

All of the cells in the table will be integers representing a population of people.

I was trying to learn some new syntax and decided to use intersect and except . I wanted to make the thing 1 and thing 2 s variables so I put the below query into a stored procedure.

CREATE PROC Findoddsratio (@diag1 NVARCHAR(5), 
                           @diag2 NVARCHAR(5)) 
AS 
    IF Object_id('tempdb..#temp') IS NOT NULL 
      DROP TABLE #temp 

    CREATE TABLE #temp 
      ( 
         squarenumber CHAR(1), 
         counts       FLOAT 
      ) 

    INSERT INTO #temp 
                (squarenumber, 
                 counts) 
    SELECT * 
    FROM   ( 
           --both + 
           SELECT 'a'                                    AS squareNumber, 
                  Cast(Count(DISTINCT x.counts)AS FLOAT) AS counts 
           FROM   (SELECT DISTINCT ic.patid AS counts 
                   FROM   icdclm AS ic 
                   WHERE  ic.icd LIKE @diag1 
                   INTERSECT 
                   SELECT DISTINCT ic.patid AS counts 
                   FROM   icdclm AS ic 
                   WHERE  ic.icd LIKE @diag2)x 
           UNION 
           --only 1+ 
           SELECT 'b', 
                  Count(DISTINCT x.counts) 
           FROM   (SELECT DISTINCT ic.patid AS counts 
                   FROM   icdclm AS ic 
                   WHERE  ic.icd LIKE @diag1 
                   EXCEPT 
                   SELECT DISTINCT ic.patid AS counts 
                   FROM   icdclm AS ic 
                   WHERE  ic.icd LIKE @diag2)AS x 
           UNION 
           --only 2+ 
           SELECT 'c', 
                  Count(DISTINCT x.counts) 
           FROM   (SELECT DISTINCT ic.patid AS counts 
                   FROM   icdclm AS ic 
                   WHERE  ic.icd LIKE @diag2 
                   EXCEPT 
                   SELECT DISTINCT ic.patid AS counts 
                   FROM   icdclm AS ic 
                   WHERE  ic.icd LIKE @diag1)AS x 
            UNION 
            --both - 
            SELECT 'd', 
                   Count(DISTINCT x.counts) 
            FROM   (SELECT DISTINCT ic.patid AS counts 
                    FROM   icdclm AS ic 
                    EXCEPT 
                    SELECT DISTINCT ic.patid AS counts 
                    FROM   icdclm AS ic 
                    WHERE  ic.icd LIKE @diag2 
                    EXCEPT 
                    SELECT DISTINCT ic.patid AS counts 
                    FROM   icdclm AS ic 
                    WHERE  ic.icd LIKE @diag1) AS x)y 

    --i used a pivot table to make the math work out easier 
    SELECT Round(Cast(( a * d ) / ( b * c ) AS FLOAT), 2) AS OddsRatio 
    FROM   (SELECT [a], 
                   [b], 
                   [c], 
                   [d] 
            FROM   (SELECT [squarenumber], 
                           [counts] 
                    FROM   #temp) p 
                   PIVOT ( Sum(counts) 
                         FOR [squarenumber] IN ([a], 
                                                [b], 
                                                [c], 
                                                [d]) ) AS pvt)t

ICDCLM is a table with a structure like patid=int, icd=varchar(5)

There are ~ one million rows in ICDCLM . When I run this query without making it a stored procedure, it runs in seconds. If I try to exec FindsOddsRation 'thing1%','thing2%' . It runs and runs, but never returns anything (> 2 minutes). What could be the difference in the stored procedure taking so long? SQL Server 2008 R2 fiddle here