Question

所以这是我的SQL

SELECT c.name AS 'name',
  COUNT(sc.condition_id) AS 'conditions_count'
FROM reviews r, strain_conditions sc
LEFT JOIN conditions c ON sc.condition_id = c.id
WHERE sc.strain_id = 1 && sc.review_id = r.id && r.moderated = 1
GROUP BY sc.condition_id
ORDER BY conditions_count DESC
LIMIT 3;

返回

+---------------+------------------+
| name          | conditions_count |
+---------------+------------------+
| Fiber Myalgia |                2 |
| Anxiety       |                2 |
| ADHD          |                1 |
+---------------+------------------+

我需要做的是GROUP_CONCAT名称的结果，所以我的最终结果就是

“纤维肌痛，焦虑，多动症”

Answer 1

您需要嵌套选择，因为LIMIT应仅适用于子查询。

SELECT GROUP_CONCAT(name) AS name
FROM
(
    SELECT c.name AS name
    FROM reviews r, strain_conditions sc
    LEFT JOIN conditions c ON sc.condition_id = c.id
    WHERE sc.strain_id = 1 && sc.review_id = r.id && r.moderated = 1
    GROUP BY sc.condition_id
    ORDER BY conditions_count DESC
    LIMIT 3  
) AS T1

如果您希望按降序排序，则应向ORDER BY添加GROUP_CONCAT。

SELECT GROUP_CONCAT(name ORDER BY conditions_count DESC) AS name
FROM
(
     -- your query here
) AS T1

如果您还想要逗号后面的空格，请使用SEPARATOR：

SELECT GROUP_CONCAT(name ORDER BY conditions_count DESC SEPARATOR ', ') AS name
FROM
(
     -- your query here
) AS T1

有关详细信息，请参阅GROUP_CONCAT的手册页。

Answer 2

将其包装在子查询中。试试这个，

SELECT GROUP_CONCAT(f.name) as `name`
FROM
(
    SELECT c.name AS 'name',
           COUNT(sc.condition_id) AS 'conditions_count'
    FROM reviews r, strain_conditions sc
    LEFT JOIN conditions c ON sc.condition_id = c.id
    WHERE sc.strain_id = 1 && sc.review_id = r.id && r.moderated = 1
    GROUP BY sc.condition_id
    ORDER BY conditions_count DESC
    LIMIT 3
) f

Answer 3

您需要将其放在子选择中：

SELECT GROUP_CONCAT(name) AS name
FROM
(
  SELECT c.name AS 'name',
    COUNT(sc.condition_id) AS 'conditions_count'
  FROM reviews r, strain_conditions sc
  LEFT JOIN conditions c ON sc.condition_id = c.id
  WHERE sc.strain_id = 1 && sc.review_id = r.id && r.moderated = 1
  GROUP BY sc.condition_id
  ORDER BY conditions_count DESC
  LIMIT 3
) x

GROUP_CONCAT一个select语句

3 个答案: