perl - compare two column of two SQL query from 2 databases - sql

Question

in perl, i want to insert year and parti from database 2 to database 1 if name from database 1 and name from database 2 is equal
database 1 database 2
----------------------------------- ----------------------------------
table truc table truc2
----------------------------------- ----------------------------------
id name year parti id name year parti
----------------------------------- ----------------------------------
1 Lapin 14 Lapin 2014 MODEM
118 Koala 33 Murène 1347 EELV
14 Murène 2 Ragondin 4218 SP
3 Ragondin 3 Koala 1512 CPNT
i want the result:
database 1
-----------------------------------
table truc
-----------------------------------
id name year parti
-----------------------------------
1 Lapin 2014 MODEM
118 Koala 1512 CPNT
14 Murène 1347 EELV
3 Ragondin 4218 SP
thanks for any response,
my code of perl and sql are here

Answer 1

Read from one database and update in the second one:
my $query2 = $db2->prepare('SELECT id, name, sex, year, parti FROM truc2');
my $query1 = $db1->prepare('UPDATE truc'
. ' SET year = ?, parti = ? WHERE name = ?');
$query2->execute;
while (my #row = $query2->fetchrow_array) {
$query1->execute($row[3], $row[4], $row[1]);
}
Tested with:
#!/usr/bin/perl
use warnings;
use strict;
use utf8;
use feature qw{ say };
use open IO => ':encoding(UTF-8)', ':std';
use DBI;
my $db1 = DBI->connect('dbi:SQLite:dbname=:memory:', "", "",
{ sqlite_unicode => 1 });
$db1->do('CREATE TABLE truc'
. ' (id INT, name TEXT, sex VARCHAR, year INT, parti TEXT)');
my $db2 = DBI->connect('dbi:SQLite:dbname=:memory:', "", "",
{ sqlite_unicode => 1 });
$db2->do('CREATE TABLE truc2'
. ' (id INT, name TEXT, sex VARCHAR, year INT, parti TEXT)');
my $insert1 = $db1->prepare('INSERT INTO truc (id, name, sex)'
. ' VALUES (?, ?, ?)');
$insert1->execute(#$_) for [ 1, 'Lapin', 'M'],
[118, 'Koala', 'F'],
[ 14, 'Murène', 'A'],
[ 3, 'Ragondin', 'F'];
my $insert2 = $db2->prepare('INSERT INTO truc2 (id, name, sex, year, parti)'
. ' VALUES (?, ?, ?, ?, ?)');
$insert2->execute(#$_) for [14, 'Lapin', 'A', 2014, 'MODEM'],
[33, 'Murène', 'F', 1347, 'EELV'],
[ 2, 'Ragondin', 'M', 4218, 'SP'],
[ 3, 'Koala', 'F', 1512, 'CPNT'];
my $query2 = $db2->prepare('SELECT id, name, sex, year, parti FROM truc2');
my $query1 = $db1->prepare('UPDATE truc'
. ' SET year = ?, parti = ? WHERE name = ?');
$query2->execute;
while (my #row = $query2->fetchrow_array) {
$query1->execute($row[3], $row[4], $row[1]);
}
my $verify = $db1->prepare('SELECT * from truc');
$verify->execute;
while (my #row = $verify->fetchrow_array) {
say "#row";
}

Answer 2

UPDATE database1.truc
JOIN database2.truc2 ON database1.truc.name = database2.truc2.name
SET database1.truc.year = database2.truc2.year
database1.truc.parti = database2.truc2.parti;
No binding, no copying data into arrays, no loss of id, etc.