Update last child id in parent table using mysql
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by Sam Saffron
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Published on 2010-03-08T01:43:45Z
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2010/03/08
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mysql
|mysql-query
Given the following tables:
Topic
id, last_updated_child_id
Response
id, topic_id, updated_at
How do I update the Topic table so the last_updated_child_id
is equal to the latest response id (based on date).
So for example given:
Topic id last_updated_child_id -- ----------------------- 1 null 2 null 3 null Response id topic_id updated_at -- ---- ---- 1 1 2010 2 1 2012 3 1 2011 4 2 2000
I would like to execute an UPDATE
statement that would result in the Topic table being:
id last_updated_child_id -- ----------------------- 1 2 2 4 3 null
Note: I would like to avoid temp tables if possible and am happy for a MySQL specific solution.
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