LINQ系列：Linq to Object串联操作符

public static IQueryable<TResult> Cast<TResult>(this IQueryable source);

public static IQueryable<TSource> Concat<TSource>(this IQueryable<TSource> source1, IEnumerable<TSource> source2);

var expr = context.Categories
    .Select(c => c.CategoryName)
    .Concat(
        context.Products
        .Select(p => p.ProductName)
    );

foreach (var item in expr)
{
    Console.WriteLine(item);
}