-- DropForeignKey
ALTER TABLE `sales` DROP FOREIGN KEY `sales_customer_id_fkey`;

-- AlterTable
ALTER TABLE `sales` ADD COLUMN `walk_in_mobile` VARCHAR(20) NULL,
    ADD COLUMN `walk_in_name` VARCHAR(255) NULL,
    MODIFY `customer_id` BIGINT UNSIGNED NULL;

-- AddForeignKey
ALTER TABLE `sales` ADD CONSTRAINT `sales_customer_id_fkey` FOREIGN KEY (`customer_id`) REFERENCES `customers`(`id`) ON DELETE SET NULL ON UPDATE CASCADE;