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 return = 'bkp_' . date('Ymd') . '_' . $tableName;

 return 'bkp_' . date('Ymd') . '_' . $tableName;

Also note it recommends declaring the visibility on constants when using PHP 7.1 or later- hopefully it is running on 7.3 or newer given current LTS.

Presuming the code is running PHP 7.3 or newer- type declarations can be added for arguments and return values of methods, plus with PHP 7.4 they can be added to properties.

Also note it recommends declaring the visibility on constants when using PHP 7.1 or later.

Type declarations can be added for arguments and return values of methods, plus with PHP 7.4 they can be added to properties.

if ($target === 'live') {
    if (preg_match("/{$name}=([^;]*)/", Yii::$app->getDb()->dsn, $match)) {
        return $match[1];
    }
} else {
    if (preg_match("/{$name}=([^;]*)/", Yii::$app->db_backup->dsn, $match)) {
        return $match[1];
    }
}

if ($target === 'live') {
    $dsn = Yii::$app->getDb()->dsn;
} else {
    $dsn = Yii::$app->db_backup->dsn;
}
if (preg_match("/{$name}=([^;]*)/", $dsn, $match)) {
    return $match[1];
}

    $dsn = $target === 'live' ? Yii::$app->getDb()->dsn : Yii::$app->db_backup->dsn;

if ($target === 'live') {
    if (preg_match("/{$name}=([^;]*)/", Yii::$app->getDb()->dsn, $match)) {
        return $match[1];
    }
} else {
    if (preg_match("/{$name}=([^;]*)/", Yii::$app->db_backup->dsn, $match)) {
        return $match[1];
    }
}
throw new Exception("Unable to extract the db Name");

if ($target === 'live') {
    $dsn = Yii::$app->getDb()->dsn;
} else {
    $dsn = Yii::$app->db_backup->dsn;
}
if (preg_match("/{$name}=([^;]*)/", $dsn, $match)) {
    return $match[1];
}
throw new Exception("Unable to extract the db Name");

$dsn = $target === 'live' ? Yii::$app->getDb()->dsn : Yii::$app->db_backup->dsn;