On Friday 20 October 2006 15:15, Richard Hosking wrote:
> item_1 VARCHAR(20) NOT NULL,
> item_2 VARCHAR(20),
> item_3 VARCHAR(20),
> item_4 VARCHAR(20),
> item_5 VARCHAR(20),
Don't artificially restrict yourself to 5 items - also makes searching for
billed items eg for statistics a lot harder
your transaction will have one or more items.
do instead:
create table items (
id serial primary key,
transaction_id integer references transactions(id),
...
);
You are not likely to ever run lots of queries/time over and over again for
all items of a given billing transaction, so there is no advantage in
denormalizing here
Re table name "transaction" - this is a reserved word in many SQL dialects.
rather call it billing_transaction or invoice or some such
It also makes SQL code more readable if you use plural for all table names -
only realized that myself afetr reading a lot of RoR code
Horst
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