Re: Perl DBI - Bind variable when query is inserted as part of db column

in reply to Perl DBI - Bind variable when query is inserted as part of db column

What do you mean by "inserting a query into another query"?

Maybe you want to insert the results of the first query into the second one. This example shows how to do it with DBD::SQLite, some other databases can't have more than one prepared statement per db handle, so you'd need to connect more than once.

#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

use DBI;

my $db = 'DBI'->connect('dbi:SQLite:;db=:memory:', "", "");

$db->do('CREATE TABLE t1 (id INT, name TEXT, quantity INT)');
$db->do('CREATE TABLE t2 (id INT, quantity INT)');

my $populate = $db->prepare(
    'INSERT INTO t1 (id, name, quantity) VALUES (?, ?, ?)');
$populate->execute(@$_)
    for [ 1, 'John', 12 ],
        [ 2, 'Jane', 14 ],
        [ 3, 'Jack', 16 ],
        [ 5, 'Joe',  22 ],
        [ 6, 'Josh', 27 ];

my $insert = $db->prepare('INSERT INTO t2 (id, quantity) VALUES (?, ?)
+');

my $query1 = $db->prepare(
    'SELECT id, quantity FROM t1 WHERE name LIKE ? AND id > ?');
$query1->bind_param(1, 'J%');
$query1->bind_param(2, 2);
$query1->execute;
while (my @row = $query1->fetchrow_array) {
    $insert->execute(@row);
}

my $verify = $db->prepare('SELECT * FROM t2');
$verify->execute;
my @row;
say "@row" while @row = $verify->fetchrow_array;
[download]

Or you want to create a "SELECT INTO" statement. SQLite doesn't support this syntax directly, but features a similar construct that you can use:

#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

use DBI;

my $db = 'DBI'->connect('dbi:SQLite:;db=:memory:', "", "");

$db->do('CREATE TABLE t1 (id INT, name TEXT, quantity INT)');
$db->do('CREATE TABLE t2 (id INT, quantity INT, action INT)');

my $populate = $db->prepare(
    'INSERT INTO t1 (id, name, quantity) VALUES (?, ?, ?)');
$populate->execute(@$_)
    for [ 1, 'John', 12 ],
        [ 2, 'Jane', 14 ],
        [ 3, 'Jack', 16 ],
        [ 5, 'Joe',  22 ],
        [ 6, 'Josh', 27 ];

my $insert = $db->prepare(
    'INSERT INTO t2 (action, id, quantity)'
    . ' SELECT ?, id, quantity FROM t1 WHERE name LIKE ? AND id > ?');

$insert->bind_param(1, 100);
$insert->bind_param(2, 'J%');
$insert->bind_param(3, 2);
$insert->execute;

my $verify = $db->prepare('SELECT * FROM t2');
$verify->execute;
my @row;
say "@row" while @row = $verify->fetchrow_array;
[download]

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