Re: updating a field using contents of another (json) field

[Rick James]

> update p3h0i_k2_items set params = (select params from p3h0i_k2_items where id = 300) where id = 268;

That syntax seems OK unless you are running a version of MySQL older than 4.1. What is the exact error message?

See the online page about multi-table updates.
I got lost on the significance of `params` and JSON, so my UPDATE below may not be doing what you asked.

UPDATE    Items a
    JOIN  Items b SET
        a.title = b.title,
        a.catid = b.catid,
        a.params = b.params,
        ...
    WHERE  a.id = 300
      AND  b.id = 268;

> If I can get the query working I'll set it to update all the records in a category.

WHERE a.catid = ... instead of WHERE a.id = 300?

> There are upwards of 500 items to fix;

By "items", are you referring to rows in the table? Or fields in the table?