On Sat, 2002-09-28 at 02:36, D. A. wrote:
> I am storing a schedule of services in a restaurant database (e.g.
> breakfast, lunch...), and want to be able to order the results by the day
> of the week. The table is as follows.
> Table "schedule"
> Column | Type | Modifiers
> business_id | integer | not null
> day | character varying(20) |
> start | time without time zone |
> finish | time without time zone |
> service | character varying(30) |
> The day collumn will hold the days of the week "Monday", "Tuesday"... etc.
> When I retrieve the data, I want to be able to sort by the days in
> cronological order rather than in alphabetic order.
> My questions are these:
> 1) Is it possible to use "order by" in conjunction with a list of strings
> to tell it how to order the results?
You could write a function to convert day names into numbers and sort on
the output of that function.
> 2)Is there a way to store days of the week that is better than simply
> using varchar and performing a check. I read about the time data formats
> and they all seem to be more applicable to absolute times rather than
> simply a day of the week. I also thought about storing the days as a
> number between 1 and 7 then converting for display (1=Monday,
> 2=Tuesday...), but that didn't feel clean to me.
It seems cleaner to me. It would take less storage and be easier to
validate ("CONSTRAINT "valid day" CHECK (day >= 0 AND day < 7)").
Create a view that has an additional dayname column defined as "CASE
WHEN day = 0 THEN "Sunday" WHEN day = 1 THEN "Monday" ... END" Then you
can sort by day but select dayname.
Oliver Elphick Oliver(dot)Elphick(at)lfix(dot)co(dot)uk
Isle of Wight, UK
GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839 932A 614D 4C34 3E1D 0C1C
"Blessed is the man that endureth temptation; for when
he is tried, he shall receive the crown of life, which
the Lord hath promised to them that love him."
In response to
pgsql-novice by date
|Next:||From: Roland Roberts||Date: 2002-09-29 00:30:06|
|Subject: Re: "order by" days of the week|
|Previous:||From: Ludwig Lim||Date: 2002-09-28 07:28:50|
|Subject: Is this error message PostgreSQL related?|