*UPDATED*: How to drop all tables from database using Yii2. Includes disabling foreign key checks, fixed app() and execute().

yii2-drop-all-tables-from-database.php

<?php

Yii::$app->db->createCommand("SET foreign_key_checks = 0")->execute();
$tables = Yii::$app->db->schema->getTableNames();

foreach ($tables as $table) {
    Yii::$app->db->createCommand()->dropTable($table)->execute();
}

Yii::$app->db->createCommand("SET foreign_key_checks = 1")->execute();