servicio-autos-api/migrations/m240816_231235_obras_clave_unique.php

<?php

use yii\db\Migration;

/**
 * Class m240816_231235_obras_clave_unique
 */
class m240816_231235_obras_clave_unique extends Migration
{
    /**
     * {@inheritdoc}
     */
    public function safeUp()
    {
        $this->addColumn('Obra', 'clave', $this->string());
        $this->createIndex(
            'id-claveObra-unique',
            'Obra',
            'clave',
            true 
        );
    }

    /**
     * {@inheritdoc}
     */
    public function safeDown()
    {
        $this->dropIndex(
            'id-claveObra-unique',
            'Obra'
        );
        $this->dropColumn('Obra', 'clave');
    }

    /*
    // Use up()/down() to run migration code without a transaction.
    public function up()
    {

    }

    public function down()
    {
        echo "m240816_231235_obras_clave_unique cannot be reverted.\n";

        return false;
    }
    */
}