Transpose or unpivot every other column

问题:

Basically what I am trying to do is transpose every other column to a row with the following columns data beside it.

The source can have only two columns up to one-thousand and millions of rows. I am only doing this on a per-row basis. I have tried doing a "UNION ALL" however this is incredibly slow when dealing with hundreds of columns in a large table.

Possible solutions are using UNPIVOT although every example I can find is doing something different from what I want.

Example: Before Query

Columns...
Apple | Apple Data | Banana | Banana  Data | Cranberry | Cranberry  Data | .... 

Data Returned... 
IOWA_PL_RLA | 1 | IOWA_PL_MATH | 1 | IOWA_SS_RLA 684 .....

Example: After Query

MeasureID  Score
CRCT_PL_RLA   | 1 
CRCT_PL_MATH  | 1 
CRCT_SS_RLA   |684 
.....

Hopefully I have explained myself enough that someone can help as I am only moderately experienced in T-SQL. If more information is needed please let me know.

回答1:

If you are using SQL Server 2008, I think you should look into using the CROSS APPLY (VALUES) technique:

http://www.sqlservercentral.com/articles/CROSS+APPLY+VALUES+UNPIVOT/91234/

Basically, it goes like this:

SELECT
  x.NewColumn1,
  x.NewColumn2
FROM YourTable t
CROSS APPLY (
    VALUES
        (t.OldColumn1, t.OldColumn2),
        (t.OldColumn3, t.OldColumn4),
        ...
) x (NewColumn1, NewColumn2);

Here's a runnable example: http://sqlfiddle.com/#!3/9a9d2/5/0