Re: Normalization and regexp

In order to reduce the number of rows in the p_code table, you could
modify it so that it had the following columns:

create table p_code (
pCode_Start varchar(3),
pCode_End varchar(3),
tariff integer,
primary key(pCode_Start, pCode_End)
);

If you need to insert a single code, use the following:

insert into pCode('G4V','G4V',14);

and a range as follows:

insert into pCode('G8E', 'G8G',14);

Your select statement is now:

SELECT price FROM price_weight pw, p_code pc
WHERE pc.tarrif = pw.tarrif
AND pCode_Start <= 'G8F'
AND pCode_End >= 'G8F'
AND weight = '1.0';

I think that should work OK...

John Sidney-Woollett

MT said:
> Hi,
>
> Since Canada Post hasn't programmed their automated web tools for
> calculating transportation costs to work with anything outside of Windows
> Internet Explorer, I'm obliged to write a web based program optimized for
> all those *other* browsers, myself. Part of this task requires that I set
> up tables in postgresql that match postal codes to transportation cost.
>
> Canada Post provides a booklet for calculating transportation cost based
> on package weight and the first three characters of the postal code
> sequence. For instance, if I want to send a package to an address that
> includes G8F 1X1 as the postal code, I take the first 3 characters G8F and
> look them up in table 1.
>
> Table 1
>
> PostalCode Tarrif number
> ---------------------------
> G4V 14
> G8E-G8G 14
> G4R-G4S 13
>
> Since G8F falls in the G8E-G8G range, I now know that the tarrif number is
> 14. Taking the number 14, I go to table 2
>
> Table 2
>
> For tarrif Code 14
> Weight(kg) Price
> ----------------------
> 1.0 5.37
> 1.5 5.61
> 2.0 5.82
>
> If the weight of my package is 1kg, the price is 5.37 to send the package
> to the address bearing G8F as the first 3 characters of the postal code.
>
> To render this in the database, I have done the following:
>
> _____________________________
> p_code |
> =============================
> pcode_id | tarrif |
> -----------------------------
> G4V | 14 |
> -----------------------------
> G8E | 14 |
> -----------------------------
> G8F | 14 |
> -----------------------------
> G8G | 14 |
> -----------------------------
> G4R | 13 |
> -----------------------------
> G4S | 13 |
> -----------------------------
>
> __________________________________
> price_weight |
> ==================================
> tarrif | weight(kg)| price |
> ----------------------------------
> 14 | 1.0 | 5.37 |
> ----------------------------------
> 14 | 1.5 | 5.61 |
> ----------------------------------
> 14 | 2.0 | 5.82 |
> ----------------------------------
> 13 | 1.0 | 5.20 |
> ----------------------------------
> 13 | 1.5 | 5.32 |
> ----------------------------------
> 13 | 2.0 | 5.42 |
>
>
> Therefore my sql statement would look something like this:
>
> SELECT price FROM price_weight
> WHERE p_code.tarrif = price_weight.tarrif
> AND pcode = 'G8F'
> AND weight = '1.0';
>
> I think this will work, but before I proceed, I'd like to ask 2 questions:
>
> 1.
> Is it possible to further normalize the data in the p_code and
> price_weight tables above?
>
> 2.
> Is it possible to abbreviate the number of records in the p_code table
> using regular expressions. For instance, to avoid repetition, I thought
> I'd use regular expressions, so that instead of entering the postal code
> into separate rows as such:
>
> G4V 14
> G8E 14
> G8F 14
> G8G 14
>
> I could do something like this:
>
> (G4V | G8[E-G]) 14
>
> Somehow I don't think this is possible, but I'm looking for any way to
> minimize the number of postal codes that I have to enter, since there's a
> lot of them.
>
> Anyway, I realize these questions may have more to do with database design
> than postgresql per se. If there's a better place to ask them, please
> point me in the right direction.
>
> Thanks,
>
> Mark
>
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