如何按逗号分隔的数据分组 [英] How to Group By This Comma-Delimited Data

问题描述

我有这样的数据:

ID  Book    Author
1   Book A  Andy, Brian
2   Book B  Andy, Charlie
3   Book C  Brian

如何按数据分组，以便我可以这样:

How to group by the data so i can get like this:

Author  Count
Andy    2
Brian   2
Charlie 1

推荐答案

如果我们假设你有一个规范化的结构，你只需要:

If we assume you have a normalized structure, you simply need to :

SELECT a.author, count(*) 
FROM books b
INNER JOIN author a ON a.author_id=b.author_id
GROUP BY a.author

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