Mysql 创建表时，外键约束的格式不正确

我有两个SQL查询，当我编写第二个查询时，它会删除一个SQL错误，如“外键约束格式不正确”。我不知道，第一个表的ID是主键

CREATE TABLE clients(
    id_client INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(32),
    surname VARCHAR(32),
    dni VARCHAR(32),
    address VARCHAR(32),
    type CHAR
)

另一方面：

CREATE TABLE clients_vehicles(
    id_client_vehicle INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    license_plate VARCHAR(32),
    num_chasis VARCHAR(32),
    color VARCHAR(32),
    brand VARCHAR(32),
    model VARCHAR(32),
    model_version VARCHAR(32),
    fuel_type CHAR,
    km INT,
    cv INT,
    type CHAR,
    id_client INT NOT NULL,
    FOREIGN KEY (id_client) REFERENCES clients(id_client)
)

---

clients\u vehicles.id\u client

是

INT

而

clients.id\u client

是

UNSIGNED INT

。存在类型不匹配

将

UNSIGNED INT

更改为

INT

，它将工作

INT

UNSIGNED