In my experience, "algorithmic knowledge" doesn't indicate that you'll be any damn good at SQL. I think the time it takes depends on what competence looks like

In my experience, "algorithmic knowledge" doesn't indicate that you'll be any damn good at SQL. I think the time it takes depends on what competence looks like for your use case. If we're talking about just retrieving records that match certain criteria, you might get over the hump of understanding joins faster than a non-programmer, and you could probably write 90% of the queries you'll ever need in a week or less. Reporting is different. Designing schema is different. Troubleshooting data issues in a poorly designed database is way different. Tuning queries and indexes for performance is way different. Not all use cases include those things.