Question

select gmt from history.cachemap order by gmt asc limit 0,1;
..this returns gmt: 2012-05-03
select gmt from history.cachemap order by gmt desc limit 0,1;
..this returns gmt: 2012-09-15

A little background on the database I’m working with, I’m trying to get the earliest and latest date fields from a list of several million records.

Earlier this week I posted this question:

How to combine three MySQL queries into one?

This question was answered perfectly, but doesn’t apply to this type of query.

Answer 1

I think the best way is to use the max and min functions. You can get the results as one row:

select min(gmt), max(gmt)
from history.cachemap

This is the most efficient solution, since it involves only one pass through the data.

Alternatively, you can put this into two rows, using union all:

select 'min' as which, min(gmt)
from history.cachemap union all
select 'max', max(gmt)
from history.cachemap

UNION/UNION ALL does not return rows in a specified order, so you should include information on which is which (or order them explicitly).