将SELECT行的唯一结果放在一行中

SELECT column, GROUP_CONCAT(expression SEPARATOR separator)
FROM table
GROUP BY column;

+----+-------+
| id | name  |
+----+-------+
| 1  | Alice |
| 2  | Bob   |
| 3  | Alice |
+----+-------+

SELECT name, GROUP_CONCAT(name SEPARATOR ', ')
FROM students
GROUP BY name;

+-------+---------------------+
| name  | GROUP_CONCAT(name)  |
+-------+---------------------+
| Alice | Alice, Alice        |
| Bob   | Bob                 |
+-------+---------------------+

SELECT GROUP_CONCAT(column SEPARATOR ' ')
FROM table;