Is it possible to Update single/multiple columns using "group by"

I am running group by on 4 columns of two tables. I have unique ID column in two tables. I want to mark both the tables occurrences column to SINGLE/MULTIPLE based on the 4 columns. Is there any w开发者_C百科ay to update based on the results of group by?.

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As longneck noted, your description is pretty vague.

However, to answer your question generally, it IS possible to run an update based on the results of another query:

UPDATE your_update_table
FROM your_update_table
JOIN
(
    # Insert your query (with GROUP BYs and all) here
) AS subquery_join ON subquery_join.id = your_update_table.id
SET your_update_table.column = subquery_join.some_value

A more explicit answer would require a more detailed explanation of the problem.