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}");
}
}
private static void SeedData()
{
using (var db = new CatsDbContext())
{
db.Database.Migrate();
db.ChangeTracker.AutoDetectChangesEnabled = true;
for (int i = 1; i <= 10000; i++)
{
var owner = new Owner
{
Name = $"Owner {i}"
};
for (int j = 1; j <= 10; j++)
{
owner.Cats.Add(new Cat
{
Name = $"Cat {i} {j}",
Color = j % 2 == 0 ? "Black" : "White",
BirthDate = DateTime.Now.AddDays(-j),
Age = j
});
}
db.Owners.Add(owner);
if (i % 200 == 0)
{
db.SaveChanges();
Console.Write(".");
}
}
}
}
