查询学生在成绩表中最大成绩，没有为0

表数据：

stu

score

 

 

SELECT stu.*,IF(ISNULL(MAX(score.`score`)),0,MAX(score.`score`)) AS maxscore FROM stu LEFT JOIN score ON score.`stu_id`=stu.`id` WHERE stu.`id`=2

SELECT stu.*,IFNULL( MAX(score.`score`),0) AS maxscore FROM stu LEFT JOIN score ON score.`stu_id`=stu.`id` WHERE stu.`id`=2

结果：