Basically what I want to do is copy the value of a column from one table to another column in another table.
The query I am using is:
UPDATE t1
SET prod
-
You should just being doing the update across a join like this
UPDATE
t1 INNER JOIN t2 ON t1.variant_id = t2.variant_id
SET t1.product_code = t2.value
WHERE t2.key_id = 10
AND t2.value IS NOT NULL
There is no need to worry about nulls in that case as the inner join will only select rows where the variant_id exists in both tables.
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