Question

I have a function which produces 5 columns of results (and say for example, 10 rows).

This data is being inserted into a Key-Value table and so I need to get it into the format of the 50 rows for insertion.

At the moment I am currently selecting each column five times and union-ing the results together. As it is the same query being run five times, but only one column selected each time this seems very inefficient. Ideally I could only run the query once, but transpose the data from 5 x 10, to 1 x 50.

So if my query returns two rows of: [ID],[ColA],[ColB],[ColC],[ColD],[ColE]

I would like to get this into the format:

[ID0],[ColA0]

[ID0],[ColB0]

[ID0],[ColC0]

[ID0],[ColD0]

[ID0],[ColE0]

[ID1],[ColA1]

[ID1],[ColB1]

.

.

Answer 1

Just replace the CTE with your data and you should be good to go.

;WITH CTE AS
(   SELECT 1 [ID], 'A1' [ColA], 'B1' [ColB], 'C1' [ColC], 'D1' [ColD], 'E1' [ColE]
    UNION ALL
    SELECT 2 [ID], 'A2' [ColA], 'B2' [ColB], 'C2' [ColC], 'D2' [ColD], 'E2' [ColE]
)
SELECT  [ID], [ColumnName], Value
FROM    CTE
        UNPIVOT
        (   Value
            FOR [ColumnName] IN ([ColA], [ColB], [ColC], [ColD], [ColE])
        ) upvt