Maybe you already do, but I've had this exact challenge in the past as well and what has worked best is to send them some SQL queries that do it the "right" way. Often times I think they just don't want to deal with the problem: it's hard, it's uncomfortable, and nobody "up the chain" will care about it. There's plenty of reason not to want to do it.

But giving them the query, or writing the migration for them, often takes care of both one and two. I've even seen this approach ignite a passion for query optimization as it "clicked" for them!