Oracle SQL update based on subquery between two tables

Question

I am currently writing update statements to keep a query-able table constantly up to date. The schema is identical between both tables and the contents are not important:

Answer 1

As you've noticed, you have no selectivity to your update statement so it is updating your entire table. If you want to update specific rows (ie where the IDs match) you probably want to do a coordinated subquery.

However, since you are using Oracle, it might be easier to create a materialized view for your query table and let Oracle's transaction mechanism handle the details. MVs work exactly like a table for querying semantics, are quite easy to set up, and allow you to specify the refresh interval.