This is similar to this question, but I want to avoid a second SQL query if possible.

I have a dataset which looks like this:

SELECT [id], [category], [data]... 
FROM MyDatabase.MyTable ... 

which returns this data set as result:

ID	Category	More Data
1	foo	DATA 1...
2	bar	DATA 2...
3	foo	DATA 3...
4	bar	DATA 4...
3	baz	DATA 5...
4	bar	DATA 6...