选择查询以通过合并两列来获得结果

Question

I have a table like below :

Id   Price1  Price2
3     30       20
3     40       20
3     50       20

I want to write a query to get a below result :

Desired Ouput :

RowNo  Id Price
1       3  20
2       3  30
3       3  40
4       3  50

Please help!!

Answer 1

Use Cross apply to unpivot the data and generate row number

SELECT Row_number()OVER(ORDER BY price) AS Rowno,*
FROM   (SELECT DISTINCT Id,
                        Price
        FROM   (VALUES (3,30,20),
                       (3,40,20),
                       (3,50,20) ) tc ( Id, Price1, Price2)
               CROSS apply (VALUES (Price1),
                                   (Price2)) Cs (Price)) A 

Result :

╔═══════╦════╦═══════╗
║ Rowno ║ Id ║ Price ║
╠═══════╬════╬═══════╣
║     1 ║  3 ║    20 ║
║     2 ║  3 ║    30 ║
║     3 ║  3 ║    40 ║
║     4 ║  3 ║    50 ║
╚═══════╩════╩═══════╝

Answer 2

You can use union to combine the rows (so duplicates are removed). And then row_number() to calculate rownum :

select row_number() over (order by price) as rownum, id, price
from ((select id, price1 as price from t) union
      (select id, price2 from t
     ) t
order by price;