Linq and SQL, get only some data - sql

Question

I have two classes like this:
public class Book
{
public int ID { get; set; }
public string Name { get; set; }
public DateTime Date { get; set; }
public int AuthorID { get; set; }
public Author author { get; set; }
}
public class Author
{
public int ID { get; set; }
public string Name { get; set; }
public DateTime BirthDate { get; set; }
public string Place { get; set; }
}
They are linked with Foreign Key (of course AuthorID form Book and ID from Author)
I can retrieve data with this query through LINQ:
var _book = context.Book
.Where(x => x.ID == ID_I_Pass_From_FrontEnd)
.Select(x => new Book {
ID = x.ID,
Name = x.Name,
Date = x.Date,
author = new Author {ID = x.author.ID, Name = x.author.Name})
.FirstOrDefault();
In this way I get data without BirthDate and Place from Author and this is my goal.
Unfortunately I need to use SQL because I'm afraid of performances in case number of data will increase. So I started to code and with this:
var sql = string.Format("SELECT * FROM[Book] AS[x] WHERE([x].ID == ({0})), ID_I_Pass_From_FrontEnd");
var result = context.Book.FromSql(sql).Include(x => x.author).FirstOrDefault();
I can retrieve data but with BirthDate and Place. I'd like to avoid these informations.
Of course my real classes are full of columns, what I wrote in this post is just an example.
Other informations:
I'm using AZURE sql as db
I tried, in sql string, to insert INNER JOIN for join with Author table but I got error: "Sequence contains more than one matching element". Probably it is confused about same column name (ID in Book and ID in Author).
How can I achieve, with SQL string, same data of LINQ query? so how can I avoid to get data not useful in that moment?

Answer 1

Use the same projection as in pure LINQ query. There is no difference:
var _book = context.Book.FromSql(sql)
.Select(x => new Book {
ID = x.ID,
Name = x.Name,
Date = x.Date,
author = new Author {ID = x.author.ID, Name = x.author.Name})
.FirstOrDefault();