Support for NEW keyword in expression

[touyu]

--export output

CREATE TABLE `users` (
  `id` int unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `deleted_at` timestamp NULL DEFAULT NULL,
  `logical_uniqueness` tinyint(1) DEFAULT '1',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;

Input SQL

CREATE TRIGGER set_logical_uniqueness_on_users BEFORE UPDATE ON users FOR EACH ROW
SET NEW.logical_uniqueness = CASE 
    WHEN NEW.deleted_at IS NULL THEN 1 	
    WHEN NEW.deleted_at IS NOT NULL THEN NULL 
END;

Current output

found syntax error when parsing DDL "CREATE TRIGGER set_logical_uniqueness_on_users BEFORE UPDATE ON users FOR EACH ROW
SET NEW.logical_uniqueness = CASE
	WHEN NEW.deleted_at is null then 1
	WHEN NEW.deleted_at is not null then null
END": syntax error at position 128 near 'new'

Expected output

-- Apply --
CREATE TRIGGER set_logical_uniqueness_on_users BEFORE UPDATE ON users FOR EACH ROW SET NEW.logical_uniqueness = CASE WHEN NEW.deleted_at IS NULL THEN 1 WHEN NEW.deleted_at IS NOT NULL THEN NULL END;