Re: Using q() to define a query
- From: hjp@xxxxxxxxx (Peter J. Holzer)
- Date: Mon, 14 Jan 2008 11:54:11 +0100
On 2008-01-12 11:51:42 +0100, Dr.Ruud wrote:
Colin Wetherbee schreef:[...]
my $sql = q(SELECT departure_date, eq.name AS equipment,
dp.full_city AS departure_city, ap.full_city AS arrival_city,
ca.name AS carrier_name, number
FROM jsjourneys
FULL OUTER JOIN jscarriers AS ca ON jsjourneys.carrier = ca.id
FULL OUTER JOIN jsequipment AS eq ON jsjourneys.equipment = eq.id
JOIN jsports AS dp ON jsjourneys.departure_port = dp.id
JOIN jsports AS ap ON jsjourneys.arrival_port = ap.id
ORDER BY departure_date);
(As an aside, how do you guys quote your queries? I find that for
anything longer than about 60 characters, q() and '' and everything
else start to look horribly inelegant.)
my $sql = <<'SQL';
SELECT
jo.departure_date AS departure
, eq.name AS equipment
, dp.full_city AS departure_city
, ap.full_city AS arrival_city
, ca.name AS carrier_name
, jo.number
FROM
jsjourneys AS jo
SQL
I almost never use here documents because they cannot be properly
indented:
sub foo {
some;
code;
here;
if (bla) {
more;
code;
here;
my $sql = <<'SQL';
SELECT
jo.departure_date AS departure
, eq.name AS equipment
, dp.full_city AS departure_city
, ap.full_city AS arrival_city
, ca.name AS carrier_name
, jo.number
[...]
SQL
even;
more;
}
code;
here;
}
just looks terrible. Of course with SQL leading whitespace doesn't
matter so you can just indent the whole statement and just have the
dangling terminator at the left edge[1] but that doesn't work for
multiline strings in general. Putting here documents in a function of
their own as proposed by Stephen helps, but the indentation is still
inconsistent.
Since initial whitespace doesn't matter in SQL, I'd just write that as:
sub foo {
some;
code;
here;
if (bla) {
more;
code;
here;
my $sql = q{
SELECT
jo.departure_date AS departure
, eq.name AS equipment
, dp.full_city AS departure_city
, ap.full_city AS arrival_city
, ca.name AS carrier_name
, jo.number
[...]
};
even;
more;
}
code;
here;
}
(actually, I'd put the commas at the end of the lines)
As an aside, the SPL programming language[2] allows the terminator of a
here document to be indented and to strip off everything up to and
including some character from each line, so that could be written like
this:
function foo() {
some;
code;
here;
if (bla) {
more;
code;
here;
var sql = >>SQL|
|SELECT
| jo.departure_date AS departure
|, eq.name AS equipment
|, dp.full_city AS departure_city
|, ap.full_city AS arrival_city
|, ca.name AS carrier_name
|, jo.number
|[...]
SQL;
even;
more;
}
code;
here;
}
BTW, some editors recognize certain heredoc-delimiters (like SQL) and
switch language for color coding, autocompletion, etc.
That's a neat feature of course and an argument for using
here-documents.
hp
[1] No, I don't think »my $sql = <<' SQL';« is a good idea.
[2] http://www.clifford.at/spl
--
_ | Peter J. Holzer | If I wanted to be "academically correct",
|_|_) | Sysadmin WSR | I'd be programming in Java.
| | | hjp@xxxxxxxxx | I don't, and I'm not.
__/ | http://www.hjp.at/ | -- Jesse Erlbaum on dbi-users
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