How to merge fields with the same content in mysql into one piece of data

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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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