public static void DeleteCustomerRecored(string customerId)
{
using (var northwindEntities = new NorthwindEntities())
{
var customer = CustomersRepository.GetCustomerById(northwindEntities, customerId);
northwindEntities.Customers.Remove(customer);
northwindEntities.SaveChanges();
}
}
public static void AddCustomerRecord(string customerId, string companyName)
{
using (var northwindEntities = new NorthwindEntities())
{
northwindEntities.Customers.Add(new Customer
{
CustomerID = customerId,
CompanyName = companyName
});
northwindEntities.SaveChanges();
}
}
//7.Try to open two different data contexts and perform concurrent changes on the same records.
public static void TwoContexts()
{
using (var dbOne = new NorthwindEntities())
{
using (var dbTwo = new NorthwindEntities())
{
var pesho = dbOne.Customers.FirstOrDefault();
var gosho = dbTwo.Customers.FirstOrDefault();
pesho.ContactName = "Pesho";
gosho.ContactName = "Gosho";
dbOne.SaveChanges();
dbTwo.SaveChanges();
}
}
}
// 7.
// Try to open two different data contexts and perform concurrent changes on the same records.
// What will happen at SaveChanges()?
// How to deal with it?
public static void DifferentContexts()
{
using (NorthwindEntities db1 = new NorthwindEntities(), db2 = new NorthwindEntities())
{
var customer1 = db1.Customers.FirstOrDefault();
Console.WriteLine(customer1.ContactName);
customer1.ContactName = "Ivan";
var customer2 = db2.Customers.FirstOrDefault();
Console.WriteLine(customer2.ContactName);
customer2.ContactName = "Pesho";
db1.SaveChanges();
db2.SaveChanges();
}
}
public static void UpdateCustomerRecord(string customerId, string contactName)
{
using (var northwindEntities = new NorthwindEntities())
{
var customer = CustomersRepository.GetCustomerById(northwindEntities, customerId);
customer.ContactName = contactName;
northwindEntities.SaveChanges();
}
}
//2.Create a DAO class with static methods which provide functionality for inserting, modifying and deleting customers.
public static void InsertCustomer(Customer customer, NorthwindEntities db)
{
db.Customers.Add(customer);
db.SaveChanges();
}