On Apr 13, 2012, at 3:14 PM, Steinar Midtskogen wrote:
> Puneet Kishor <[email protected]> writes:
>
>> If you want the results in separate columns, you can do something like
>>
>> SELECT Min(a) minimum, 'none' maximum FROM t UNION ALL SELECT 'none'
>> minimum, Max(a) minimum FROM t;
>
> Then it does a full scan again.
>
> But Igor's suggestion "SELECT (SELECT min(unix_time) FROM table),
> (SELECT max(unix_time) FROM table)" works fine, and means less code.
>
Yes, Igor's suggestion is definitely better, but where is the full table scan?
sqlite> EXPLAIN QUERY PLAN SELECT Min(a) FROM t UNION ALL SELECT Max(a)
FROM t;
selectid|order|from|detail
1|0|0|SEARCH TABLE t USING INTEGER PRIMARY KEY (~1 rows)
2|0|0|SEARCH TABLE t USING INTEGER PRIMARY KEY (~1 rows)
0|0|0|COMPOUND SUBQUERIES 1 AND 2 (UNION ALL)
Am I missing something?
--
Puneet Kishor
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