Your solution sounds reasonable. However, if you're preparing and executing the same query or a very similar query (like the same fields from the same table with a different value for your when clause) one right after the other then you'll want to be sure you're executing the same prepared statement again. This assumes you're using placeholders. There are many reasons to do that and no reasons not to use them.

In some applications it's common to issue the same query with different values for the placeholders many times in a row. In some cases, you'd be facing a big headache to keep a prepared query in scope from one use to the next. If it's manageable in your code without a terrible hassle, reusing your prepared statements can really help your database return your data faster and perhaps even with less CPU usage. If you have a busy server or are developing for a hosted environment like a shared web server or a utility cluster (aka "cloud"), it's not just good for your users to get a bit more responsiveness, but it's part of being a good client and member of the community not to use resources from a shared pool that you could easily avoid using.