> To: [email protected]
> From: [email protected]
> Date: Tue, 10 Apr 2012 08:57:22 -0400
> Subject: Re: [sqlite] 'where a - b > 0' and 'where a > b' not the same?
>
> Jian H. L. <[email protected]> wrote:
> > The second one changes the where clause from the form of:
> > 'where a - b > 0'
> >
> > to:
> > 'where a > b'
> >
> > Shoudn't the two where clauses be the same?
>
> Only if a and b are both numeric. But strftime() returns a string. When you
> do (number - string), the string is coerced to a number, and then the
> subtraction is performed on two numbers. With comparison operators, the story
> is much more complicated. You can piece it together from
> http://sqlite.org/datatype3.html , but the bottom line is that, in the
> expression
>
> endtime + duration > strftime(...)
>
> both sides of the comparison have affinity NONE, so no type coercion is
> performed, and integers are always compared less than strings regardless of
> actual values.
>
> You can fix it, for example, by writing
>
> endtime + duration > cast(strftime(...) as integer)
>
Thank you.
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