Question

below is my sql statement, everything work fine just i dont know how to find the MAX from multiple return value. anyway here is my code, the part i having problem is marked with [].

SELECT 
(product1.CNT+product2.CNT+product3.CNT)AS CNT,
(
 IFNULL(product1.SUMAMT,0)+
 IFNULL(product2.SUMAMT,0)+
 IFNULL(product3.SUMAMT,0)
)AS AMTAMT,

[ MAX(product1.MXDT, product2.MXDT, product3.MXDT)AS MAXDT ]

FROM 

(SELECT 
 SUM(LAMT)AS SUMAMT, 
 COUNT(LAMT)AS CNT,
 IFNULL(LSUBDT,(CURDATE()-INTERVAL 9999 DAY))AS MXDT
 FROM product1 WHERE LSUBBY=1 AND RECST=1
)product1 

CROSS JOIN 
(SELECT 
 SUM(LAMT)AS SUMAMT, 
 COUNT(LAMT)AS CNT,
 IFNULL(LSUBDT,(CURDATE()-INTERVAL 9999 DAY))AS MXDT
 FROM product2 WHERE LSUBBY=1 AND RECST=1
)product2

CROSS JOIN 
(SELECT 
 SUM(LAMT)AS SUMAMT, 
 COUNT(LAMT)AS CNT,
 IFNULL(LSUBDT,(CURDATE()-INTERVAL 9999 DAY))AS MXDT
 FROM product3 WHERE LSUBBY=1 AND RECST=1
)product3

Answer 1

The function you’re looking for is called GREATEST:

...
GREATEST(product1.MXDT, product2.MXDT, product3.MXDT) AS MAXDT
....