EF Core advanced

.Where(Func<int, int> predicate) is a signature of

• IEnumerable

• IQueryable

To provide lazy loading we need to mark navigation property as _____ and the entity should not be _____

(write two words separated by space)

(a)  

TPH розшифровується як (a)  

What can IEnumerable do?

• LINQ-to-SQL

• LINQ-to-Object

• Can pass a compiled function to LINQ extensions

• Can pass an expression tree to LINQ extensions

How Include() solves N+1 problem?

• By running queries asynchronously

• Using JOIN

• By grouping big number of queries

What will be returned if LazyLoading is turned On and Off respectively ?

var countries = db.Countries.Take(3);

var capitals = new List<Capital>();

foreach(var country in countries)

{

capitals.Add(country.Capital.Name);

}

return capitals;

• On (null reference exception) | Off (null reference exception)

• On (null reference exception) | Off (returns list of Capital names)

• On (returns list of Capital names) | Off (null reference exception)

• On (returns list of Capital names) | Off (returns list of Capital names)

Which additional method(s) we can use in the explicit loading?

• Collection()

• LoadAll()

• Reference()

Сhoose the correct statement(s) about TPH

• An entire class hierarchy can be mapped to a single table

• Every class and subclass including abstract classes has its own table

• The table includes columns for all properties of all classes in the hierarchy

• Representing inheritance relationships as relational foreign key associations

Which method should we use after [Include()] to continue including further levels of related data?

• Include()

• ThenInclude()

• Select()

• ThenSelect()

n+1 problem is caused by:

• Too many joins in one query

• Too many separate queries