Question

xml文件里如何写sql语句实现年龄分组

我做的项目是springboot+mybatis框架，想做一个年龄的分组查询,下面的代码
select t1.p1 as num1,t2.p2 as num2,t3.p3 as num3,t4.p4 as num4,t5.p5 as num5 from
(select count(age) as p1 from person where age>=0 and age <=10 ) t1 INNER JOIN
(select count(age) as p2 from person where age>=11 and age <=20 ) t2 INNER JOIN
(select count(age) as p3 from person where age>=21 and age <=30 ) t3 INNER JOIN
(select count(age) as p4 from person where age>=31 and age <=40 ) t4 INNER JOIN
(select count(age) as p5 from person where age>=41 and age <=50 ) t5
在数据库里面做查询是没问题的，但是放到项目的mapper.xml文件里就报错。

Answer 1

xml 文件中 小于号 < 要用 &lt; 代替吧。 

select t1.p1 as num1,t2.p2 as num2,t3.p3 as num3,t4.p4 as num4,t5.p5 as num5 from
(select count(age) as p1 from person where age>=0 and age <11 ) t1 INNER JOIN
(select count(age) as p2 from person where age>=11 and age <21 ) t2 INNER JOIN
(select count(age) as p3 from person where age>=21 and age <31 ) t3 INNER JOIN
(select count(age) as p4 from person where age>=31 and age <41 ) t4 INNER JOIN
(select count(age) as p5 from person where age>=41 and age <51 ) t5

希望能帮到你

追问

谢谢你，改好了，可以用了。