2008/12/23 Rachmat Febfauza <mathi...@yahoo.com>:
> =================
>
> thanks to Simon. it works!!!!. but i have some question. i hope u can help me
> to explain these :
>
> 1. is it necessary or not to specify min(awal1.begin).
No. "Begin" is part of the 'group by' clause. Each distinct value of
"Begin" will be represented in the result set.
> 2. is "min(strftime("%s",akhir1."End")-strftime("%s",awal1."Begin")) as
> Difference" is more time consuming to compute than
> "strftime("%s",min(akhir1."End"))-strftime("%s",awal1."Begin") as
> Difference". i think these give the same result.
Not sure. Can see no reason for there to be a significant performance
difference.
> 3. akhir1.Category like awal1.Category || '%'. what does it mean? why is use
> || '%'???. why not to write "awal1.category = akhir1.category". it also give
> the same result.
It does not give the same result with your originally posted data set.
The like operator matches similar text values; '%' is a wildcard.
See http://www.sqlite.org/lang_expr.html#like
>
> once again, i would say thank you for ur solution. sory for my bad english.
>
You're welcome,
Rgds,
Simon
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