On Fri, 9 Jul 2004, Peter Westergaard wrote:
>
> One idea that occurs to me, and it's a tradeoff from Torsten's idea (which
> is to read the whole database, and parse out the unique rows), is to first
> execute your "SELECT DISTINCT distinct_col FROM table", and then walk
> through that, and for each one issue a "SELECT * FROM table WHERE
> distinct_col = {value} LIMIT 1" (For some reason I can't remember the
> 'LIMIT' syntax right now, so it might be LIMIT 0,1). More transactions with
> the database, but less data actually retrieved from the database. And if
> it's indexed by distinct_col, you should be fine.
It´s not to start a war, but after having to hear so much about how good
MySQL is.
What you need is a database with sub-select capability, or to have a
feature like:
SELECT DISTINT ON(col1), col2, col5 FROM table1 WHERE...
People say that they don´t need sub-selects (transactions, procedural
languages, etc.) just because the don´t have an idea of the power that the
hold.
Just a par of cents on my part.
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Universidad Nacional
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