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This article introduces the relevant knowledge of "how to merge fields with the same content of mysql into one piece of data". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

The data extracted inline from the two tables, where the category_name field has the same content. You want to merge the fields with the same content, and add the amount field to the content in the following table.

SELECT c.category_name, count (*) AS task_num, sum (t.amount) AS amount_num

FROM cs_witkey_tasks AS t www.2cto.com

INNER JOIN cs_witkey_category AS c ON t.category_id = c.cid

GROUP BY c.category_name DESC

You should use group by instead of order by.

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