$rows = $mysqli->query(<<<EOQ
SELECT ExtractValue(TestSuiteDefinition,'//test_case/@id') as name
FROM TestSuite
WHERE TestCaseId=368
EOQ
) or die($mysqli->error);
print_r($rows->fetch_all());
Utdata:
Array
(
[0] => Array
(
[0] => 141 142 143 144
)
)