MySQL如何将两行合并为一行

CREATE TABLE A (
    id INT PRIMARY KEY,
    name VARCHAR(50)
);

INSERT INTO A (id, name)
VALUES (1, 'John'),
       (2, 'Mike'),
       (3, 'Emily');

SELECT * FROM A;

+----+-------+
| id | name  |
+----+-------+
|  1 | John  |
|  2 | Mike  |
|  3 | Emily |
+----+-------+

CREATE TABLE B (
    id INT PRIMARY KEY,
    age INT
);

INSERT INTO B (id, age)
VALUES (1, 25),
       (2, 30),
       (3, 35);

SELECT * FROM B;

+----+-----+
| id | age |
+----+-----+
|  1 |  25 |
|  2 |  30 |
|  3 |  35 |
+----+-----+

SELECT A.name, B.age
FROM A
JOIN B ON A.id = B.id;

+-------+-----+
| name  | age |
+-------+-----+
| John  |  25 |
| Mike  |  30 |
| Emily |  35 |
+-------+-----+