question about how MYSQL works

[WSQuant]

I am just trying to get a feel for how MySQL works for GROUP BY functions

if i have a simple query like:

SELECT item1, SUM(item2)
FROM myTable
GROUP BY item1

and there say 100 line items in the table. and 50 versions of item1 (item1a, item1b, etc...), so the query would return 50 lines with item1 and the sum of two numbers in item2.

To do this does MySQL have to go through the whole table to find all item1a's to sum, then go through the whole table to find all item1b's to sum and so forth?

If not can someone explain to me how MySQL works for group by functions.

Thanks

[WSQuant]

No one has an answer?

[Sarah Atkinson]

Sorry but I've never used GROUP BY

[jatar_k]

there are many around that have a better intrinsic knowledge of mysql, I just look through the manual

[dev.mysql.com...]