如何将MySQL与AS&Quot；语法一起用于存储过程返回的表

在从一个在线课程学习MySQL时，我偶然发现了这个练习(或多或少，我在这里简化它):

Task 1:使用公用表表达式(CTE)优化以下查询.

SELECT CONCAT("Cl1: ", COUNT(OrderID), "orders") AS "Total" 
FROM Orders WHERE YEAR(Date) = 2022 AND ClientID = "Cl1" 
UNION 
SELECT CONCAT("Cl2: ", COUNT(OrderID), "orders") 
FROM Orders WHERE YEAR(Date) = 2022 AND ClientID = "Cl2";

这是他们的解决方案(我理解):

WITH 
CL1_Orders AS (SELECT CONCAT("Cl1: ", COUNT(OrderID), "orders") AS "Total number of orders"  
FROM Orders WHERE YEAR(Date) = 2022 AND ClientID = "Cl1"), 
CL2_Orders AS (SELECT  CONCAT("Cl2: ", COUNT(OrderID), "orders") 
FROM Orders WHERE YEAR(Date) = 2022 AND ClientID = "Cl2")
SELECT * FROM CL1_Orders UNION SELECT * FROM CL2_Orders;

正如在课程的前一节中我使用存储过程一样，我想修改解决方案并使用它们.我写了下面的代码:

DELIMITER //
CREATE PROCEDURE totalOrders (IN client VARCHAR(10))
BEGIN
    SELECT CONCAT(client, ": ", COUNT(OrderID), "orders") 
    FROM Orders 
    WHERE YEAR(Date) = 2022 AND ClientID = client;
END//

DELIMITER ;
WITH 
SELECT * FROM CALL totalOrders("Cl1") AS cl1,
SELECT * FROM CALL totalOrders("Cl2") AS cl2
SELECT * FROM cl1 UNION SELECT * FROM cl2;

执行它会导致语法错误ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT * FROM CALL totalOrders("Cl1") AS cl1, SELECT * FROM CALL totalOrders("Cl' at line 2

我怎么才能修好它呢？怎么啦？