MySQL查询中的问题分组

Question

我在查询时遇到问题：

SELECT a.created_by, 
CASE WHEN a.created_by_alias > ' ' THEN a.created_by_alias ELSE ua.name END AS author 
FROM #__content AS a 
LEFT JOIN #__users AS ua ON ua.id = a.created_by 
WHERE a.state='1' 
GROUP BY a.created_by 
ORDER BY author

返回的结果有点正确，但我所遇到的问题是它按ID分组但仍然返回一些重复的名称（这些名称相同但具有不同的ID）。

如果这些名称具有不同的ID，我如何对这些名称进行分组？

提前感谢您的帮助。

Answer 1

按作者分组

SELECT 
    a.created_by, 
    CASE WHEN a.created_by_alias > ' ' THEN a.created_by_alias ELSE ua.name END AS author 
FROM #__content AS a 
LEFT JOIN #__users AS ua ON ua.id = a.created_by 
WHERE a.state='1' 
GROUP BY a.created_by ,author
ORDER BY author