Perhaps I undersold myself a little. By the time I got my first job I was fairly well versed in SQL querying, and these days I feel comfortable writing what I'd consider complex queries. That is with various window functions, nested queries, recursion (though I try to avoid that) etc, and I have a good handle on what the query optimizer likes and doesn't like.

But schema design is something else. I still take my time doing that.

Especially since our application is written with backwards compatibility in mind, so changing schema after it's deployed is something we try very hard to avoid.

But yeah, when hiring we require they are comfortable writing "normal" SQL queries (multiple joins, aggregation etc).

Times have changed. If you have C# programmers and they can't do it in Entity Framework/LINQ, then they can't do it.