I agree with you here. It is a temporary table that should "FIX" the
values.
Interestingly
select name, RNDValue
from (
select 'name', random() as RNDValue
)
where RNDValue > 0;
only calls random once and works as expected.
0|Trace|0|0|0|explain select name, RNDValuefrom ( select 'name',
random() as RNDValue)where RNDValue > 0;|00|
1|OpenEphemeral|0|2|0||00|
2|Goto|0|17|0||00|
3|String8|0|1|0|name|00|
4|Function|0|0|2|random(-1)|00|
5|MakeRecord|1|2|3||00|
6|NewRowid|0|4|0||00|
7|Insert|0|3|4||08|
8|Integer|0|5|0||00|
9|Rewind|0|16|0||00|
10|Column|0|1|3||00|
11|Le|5|15|3|collseq(BINARY)|6a|
12|Column|0|0|6||00|
13|Column|0|1|7||00|
14|ResultRow|6|2|0||00|
15|Next|0|10|0||00|
16|Halt|0|0|0||00|
17|Goto|0|3|0||00|
Noah
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Igor Tandetnik
Sent: Friday, August 29, 2008 9:39 AM
To: [email protected]
Subject: Re: [sqlite] problem using random() in queries
Noah Hart <[EMAIL PROTECTED]> wrote:
> I would expect that multiple calls to random always return different
> values, even if in the same line.
>
> The fact that we are aliasing random by a column name makes no
> difference to me.
What about this:
select name, RNDValue
from (
select name, random() as RNDValue from names
)
where RNDValue > 0;
Conceptually, the inner select produces a temporary table, and the outer
works on that table. Personally, I found it surprising that random() was
still called twice per row in this case.
Igor Tandetnik
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