private static void DeleteOptimized()
{
// Makes two queries - one read and one delete
using (var db = new CatsDbContext())
{
var cat = db.Cats.Find(15);
db.Remove(cat);
db.SaveChanges();
}
// Makes one query - only delete
using (var db = new CatsDbContext())
{
var cat = new Cat {
Id = 16
};
db.Remove(cat);
db.SaveChanges();
}
// Delete multiple rows - slow
using (var db = new CatsDbContext())
{
var catsToDelete = db.Cats
.Where(c => c.Age == 9)
.Select(c => c.Id);
db.RemoveRange(catsToDelete.Select(id => new Cat {
Id = id
}));
db.SaveChanges();
}
// Delete multiple rows - fast with SQL
using (var db = new CatsDbContext())
{
db.Database
.ExecuteSqlInterpolated($"DELETE FROM Cats WHERE Age = {9}");
}
}
