这是CROSS JOIN的一个用例，它使用form_data表两次，从2个表中获取所有行的组合：

SELECT *
FROM form_data a
    CROSS JOIN form_data b
WHERE a.age + b.age = 60
    -- the following condition prevents getting a combination twice
    AND a.id < b.id

一种方法是将同一个表视为第二个表并将它们连接起来

select fd1.name as name1, fd2.name as name2, fd1.age as age1, fd2.age as age2
from form_data as fd1, form_data as fd2 
where fd1.age+fd2.age = 60

这会给予出两个匹配的名字和两个匹配的年龄。但是，这也会给出拉胡尔+舒巴姆和舒巴姆+拉胡尔。
避免这种情况的一种方法是使用id

select fd1.name as name1, fd2.name as name2, fd1.age as age1, fd2.age as age2
from form_data as fd1, form_data as fd2 
where fd1.age+fd2.age = 60 and fd2.id > fd1.id

使用该表：

CREATE TABLE IF NOT EXISTS users(
`id` int,
`name` VARCHAR(10),
`age` INT,
`role` INT
);

INSERT INTO `testing_database`.`users` (`id`,`name`,`age`,`role`)
VALUES
(1,       "Rahul",          20,              1),
(2,       "Karan",          35,              0),
(3,       "Vivek",          47,              0),
(4,       "Subam",          40,              1),
(5,       "Paras",          87,              1),
(6,       "Arjun",          18,              1),
(7,       "Ayush",          28,              0)

我已经用这个查询返回了数据：

SELECT t1.id, 
       t1.name, 
       t1.role, 
       t1.age as t1_age, 
       t2.age as t2_age,
       (t1.age  + t2.age ) as sum_age
FROM testing_database.users as t1
CROSS JOIN testing_database.users as t2
ON t1.id != t2.id
WHERE (t1.age  + t2.age) = 60