Question

I have these two lines, that do exactly the same thing. But are written differently. Which is the better practice, and why?

firstRecordDate = (DateTime)(from g in context.Datas
                                   select g.Time).Min();

firstRecordDate = (DateTime)context.Datas.Min(x => x.Time);

Answer 1

there is no semantic difference between method syntax and query
syntax. In addition, some queries, such as those that retrieve the
number of elements that match a specified condition, or that retrieve
the element that has the maximum value in a source sequence, can only
be expressed as method calls.

http://msdn.microsoft.com/en-us/library/bb397947.aspx

Also look here: .NET LINQ query syntax vs method chain

It comes down to what you are comfortable with and what you find is more readable.