Question

Are these two blocks exactly the same? Does one have any advantage over the other?

        using (var context = new TRANSITEntities())
        {
            var result = context.Table1.Where(c => c.UserCode == "123");
        }


        using (var context = new TRANSITEntities())
        {
            var result = from c in context.Table1
                         where c.UserCode == "123"
                         select c;
        }

Answer 1

Exactly the same.

You can verify this yourself by looking at the ToString()

    string query1String, query2String;
    using (var context = new TRANSITEntities())
    {
        var result = context.Table1.Where(c => c.UserCode == "123");
        query1String = result.Expression.ToString();
    }


    using (var context = new TRANSITEntities())
    {
        var result = from c in context.Table1
                     where c.UserCode == "123"
                     select c;
        var query2String = result.Expression.ToString();
    }

    Assert.AreEqual(query1String, query2String);

It should also be noted that result is NOT actually a result. It’s a non-executed/enumerated IQueryable. Meaning it’s like a SQL statement that hasn’t been run yet (sort of). If you were to do

    var t1 = result.ToArray()
    var t2 = result.ToArray()

then the query would actually be executed twice. t1 and t2 are the REAL results (an in memory array)…not result. In other words, result should really be named query And further, the example you have above will never work…because if you call ToArray on the result outside of the using block, it will fail…because you can’t run the query once the context is disposed:

    using (var context = new TRANSITEntities())
    {
        var result = context.Table1.Where(c => c.UserCode == "123");
    }
    // throws exception:
    var array = result.ToArray();