compare numbers

Question

so here is the deal, and all google search i could find has different scenarios, but nothing matching my situation :-).

this will be coded in VB.net, but since its sql syntax i can easily build it into vb later.

so i have a table from which i will grab a row with numbers: select n1, n2, n3, n4, n5 from TempTable

essentially this will come back with something like the 3, 8, 12, 5, 33

i now have a 2nd table with the same columns (n1...n5)

i need to find which rows in the 2nd table which have more or equal than 2 numbers matching from the 1st set of numbers (3 or 8 or 12 or 5 or 33).

so if the 2nd table would look like this:

4, 3, 57, 33, 1

5, 6, 87, 21, 44

65, 3, 12, 7, 8

then the query should return 2 (1st and last row)

i hope that makes sense :-)

Thank you for your help!

Answer 1

I would first normalize the 2 tables, so that there is only an ID and the value (and maybe the position if that may be relevant). Let's call them A2 and B2:

SELECT ID, 1 AS Pos, N1 AS Value FROM A 
UNION ALL
SELECT ID, 2 AS Pos, N2 AS Value FROM A 
UNION ALL
SELECT ID, 3 AS Pos, N3 AS Value FROM A 
UNION ALL
SELECT ID, 4 AS Pos, N4 AS Value FROM A 
UNION ALL
SELECT ID, 5 AS Pos, N5 AS Value FROM A

Then get only the records with 2 or more matches:

SELECT B2.ID, COUNT(*) AS Matches FROM A2 
INNER JOIN B2 ON A2.Value = B2.Value
GROUP BY B2.ID
HAVING COUNT(*) >= 2

And finally count them:

SELECT COUNT(*) FROM ...

In a single query that could look like this (but I recommend you make views for A2 and B2):

WITH A2 AS (

    -- Normalize table 1
    SELECT ID, 1 AS Pos, N1 AS Value FROM A 
    UNION ALL
    SELECT ID, 2 AS Pos, N2 AS Value FROM A 
    UNION ALL
    SELECT ID, 3 AS Pos, N3 AS Value FROM A 
    UNION ALL
    SELECT ID, 4 AS Pos, N4 AS Value FROM A 
    UNION ALL
    SELECT ID, 5 AS Pos, N5 AS Value FROM A

), B2 AS (

    -- Normalize table 2
    SELECT ID, 1 AS Pos, N1 AS Value FROM B 
    UNION ALL
    SELECT ID, 2 AS Pos, N2 AS Value FROM B 
    UNION ALL
    SELECT ID, 3 AS Pos, N3 AS Value FROM B 
    UNION ALL
    SELECT ID, 4 AS Pos, N4 AS Value FROM B 
    UNION ALL
    SELECT ID, 5 AS Pos, N5 AS Value FROM B

)
-- Count them
SELECT COUNT(*) FROM (
    -- Get only the ones with 2 or more matches
    SELECT B2.ID, COUNT(*) AS Matches FROM A2 
    INNER JOIN B2 ON A2.Value = B2.Value
    GROUP BY B2.ID
    HAVING COUNT(*) >= 2
) AS T