如何返回两行联合和每行的计数？

Question

I'm trying to take 10 columns and put into one column, take 10 more different columns into a separate column and get a count for each unique couple in a third column.

So far I've got

UNION
(SELECT a_3 as x, a_4 as y FROM result)
....
UNION
(SELECT a_19 as x, a_20 as y FROM result)

This gives me a table as follows

| x | y |
---------
| a | 1 |
| a | 2 |
| b | 1 |
| b | 3 |
etc...

I want this, however I also want a third column counting how many times each row occurs, like below

| x | y |count|
---------------
| a | 1 | 10 |
| a | 2 | 3  |
| b | 1 | 6  |
| b | 3 | 2  |
etc...

I can also do:

select count(*) from (insert above union SQL)

but then I just get a total number for the table.

Thanks!

Answer 1

SELECT X,Y,COUNT(1) AS[COUNT] FROM
(
 SELECT a_3 as x, a_4 as y FROM result
 ....
 UNION
 SELECT a_19 as x, a_20 as y FROM result
) x
GROUP BY X,Y

Answer 2

Looks like your original table design is not normalized at all.

Instead of multiple union query, you can use CROSS APPLY with Table Value Constructor to simplify the query

select  x, y, count(*) as [count]
from    [result] t
        cross apply
        (
            values (a_1, a_2), (a_3, a_4), (a_5, a_6), 
                   . . . 
                   (a_19, a_20)
        ) v (x, y)
group by x, y