我想列出所有用户使用它们的corropsonding用户类。 这里是我的表mysql GROUP_CONCAT
CREATE TABLE users (
user_id INT NOT NULL AUTO_INCREMENT,
user_class VARCHAR(100),
PRIMARY KEY (user_id)
);
INSERT INTO users VALUES
(1, '1'),
(2, '2'),
(3, '1,2');
CREATE TABLE classes (
class_id INT NOT NULL AUTO_INCREMENT,
class_name VARCHAR(100),
PRIMARY KEY (class_id)
);
INSERT INTO classes VALUES
(1, 'Class 1'),
(2, 'Class 2');
的简化版本,这是查询语句中,我尝试使用,但只返回第一个匹配的用户类,而不是作为一个希望拼接列表。
SELECT user_id, GROUP_CONCAT(DISTINCT class_name SEPARATOR ",") AS class_name
FROM users, classes
WHERE user_class IN (class_id)
GROUP BY user_id;
实际输出
+---------+------------+
| user_id | class_name |
+---------+------------+
| 1 | Class 1 |
| 2 | Class 2 |
| 3 | Class 1 |
+---------+------------+
通缉输出
+---------+---------------------+
| user_id | class_name |
+---------+---------------------+
| 1 | Class 1 |
| 2 | Class 2 |
| 3 | Class 1, Class 2 |
+---------+---------------------+
在此先感谢
+1 – WirthLuce 2012-07-05 18:22:30