PDO::beginTransaction() and foreign key violation in sqlite - php

Question

I'll use the example from SQLite help page about foreign key constrains:
Let's build 2 tables in SQLite:
CREATE TABLE artist(
artistid INTEGER PRIMARY KEY,
artistname TEXT
);
CREATE TABLE track(
trackid INTEGER PRIMARY KEY,
trackname TEXT,
trackartist INTEGER,
CONSTRAINT fk
FOREIGN KEY(trackartist) REFERENCES artist(artistid))
ON UPDATE CASCADE ON DELETE CASCADE
);
Let's add 2 records from SQLite command:
sqlite> pragma foreign_keys = ON;
sqlite> INSERT INTO artist(artistid, artistname) VALUES(null, 'Bing Crosby');
sqlite> INSERT INTO track(trackid, trackname, trackartist) VALUES(null, 'White Christmas', 1);
sqlite> SELECT * FROM artist;
1|Bing Crosby
sqlite> SELECT * FROM track;
1|White Christmas|1
Now, while the command tool does NOT allow (correctly) an insert of:
sqlite> INSERT INTO track(trackid, trackname, trackartist) VALUES(null, 'Another Track', 9);
Error: FOREIGN KEY constraint failed
php on the other hand DOES allow (incorrectly) this:
$dbh = new \PDO('sqlite:test.sq3');
$dbh->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
try {
if (!$dbh->beginTransaction())
throw new \Exception('Could not started a transaction!');
//$dbh->exec('PRAGMA foreign_keys = ON;');
$query = $dbh->prepare('PRAGMA foreign_keys = ON;');
$query->execute();
//$dbh->exec("INSERT INTO track(trackid, trackname, trackartist) VALUES(null, 'Another Track', 9);");
$query = $dbh->prepare("INSERT INTO track(trackid, trackname, trackartist) VALUES(null, 'White Christmas', 9);");
$query->execute();
$dbh->commit();
} catch (\Exception $e) {
$dbh->rollback();
}
See the violation:
sqlite> SELECT * FROM track;
1|White Christmas|1
2|Another Track|9
Any idea? Thank you!

Answer 1

The documentation says:
This pragma is a no-op within a transaction; foreign key constraint enforcement may only be enabled or disabled when there is no pending BEGIN or SAVEPOINT.