Re: join table with itself?
От | T E Schmitz |
---|---|
Тема | Re: join table with itself? |
Дата | |
Msg-id | 45F99675.5050801@numerixtechnology.de обсуждение исходный текст |
Ответ на | Re: join table with itself? ("William Leite Araújo" <william.bh@gmail.com>) |
Список | pgsql-sql |
William Leite Araújo wrote: > On 15/03/07, *T E Schmitz* <mailreg@numerixtechnology.de > <mailto:mailreg@numerixtechnology.de>> wrote: > (...) > > Try join the tables. > > SELECT present.day, present.low, (MIN(future.day)-present.day) as > > days2fall FROM history AS present JOIN history AS future ON ( > present.day < future.day AND > future.low <= present.low ) > GROUP BY present.day,present.low > ORDER BY days2fall DESC That produces the same result as my previous example but maybe the join is more efficient, Thank you for the suggestion. However, I am still stuck as to how to retrieve HIGHEST. The result set produced by the above query only contains those tuples whose LOW is lower than present.LOW. For HIGHEST, I need to look at the rows between present.day and DAYS2FALL: something like SELECT MAX (high) from history WHERE day >= present.day AND day < (present.day + days2fall) - Regards, Tarlika Elisabeth Schmitz
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