I think that SQL and LINQ are two different things that you need to learn as a .NET programmer. I also think you can learn them somewhat concurrently, depending on what you know about DB and SQL basics already.
SQL is going to be more portable knowledge that, in addition to new development, you can use on legacy projects and reporting tasks. When there's a lack of DBAs (and there almost always is), you'll probably be called up to generate a quick report for accounting/marketing/etc. with the latest numbers on this or that. Or, you might get handed a legacy VB6 app as your responsibility that has inline SQL. Understanding the SQL will be essential to almost all .NET programming jobs.
LINQ is essential to know if you're going to do something other than legacy (Framework 2.0 or 1.1) .NET programming. Sure, you can write code without using it but this won't be acceptable in organizations that don't have a huge investment in 'ancient' code.
Entity Framework brings SQL and LINQ together. So, once you have a sufficient understanding of both of them you can move forward to EF rather quickly. Remember that EF can be done with straight diagramming of DB ojects, by creating your own objects in code or by a hybrid of these techniques via partial classes. There is tremendous flexibility in it with the 4.0 and 5.0 EF versions.