static void Main()
{
// 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 ?
using (var northwind1 = new NorthwindEntities())
{
using (var northwind2 = new NorthwindEntities())
{
Console.WriteLine(new string('-', 35));
Console.WriteLine("First context");
Console.WriteLine(new string('-', 35));
var person1 = northwind1.Employees.FirstOrDefault();
Console.WriteLine("Initial:{0}", person1.FirstName);
person1.FirstName = "XAXAXA";
Console.WriteLine("Changed:{0}", person1.FirstName);
// Change by Entity state Unchanged Modified Detached
var dbEntry = northwind1.Entry(person1);
dbEntry.State = EntityState.Unchanged;
northwind1.SaveChanges();
Console.WriteLine(new string('-', 35));
Console.WriteLine("Second context");
Console.WriteLine(new string('-', 35));
var person2 = northwind2.Employees.FirstOrDefault();
Console.WriteLine("Initial:{0}", person2.FirstName);
person2.FirstName = "UHAHAH";
Console.WriteLine("Changed:{0}", person2.FirstName);
northwind2.SaveChanges();
}
}
}
static void Main()
{
// 6.Create a database called NorthwindTwin with the same structure as Northwind using the features from DbContext.
// Find for the API for schema generation in MSDN or in Google.
// Get the application configuration file.
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
// Create a connection string element and save it to the configuration file.
// Create a connection string element.
ConnectionStringSettings csSettings =
new ConnectionStringSettings("NorthwindEntities",
@"metadata=res://*/NorthwindModel.csdl|res://*/NorthwindModel.ssdl|res://*/NorthwindModel.msl;provider=System.Data.SqlClient;provider connection string="data source=.;initial catalog=NorthwindTwin;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework"", "System.Data.EntityClient");
// Get the connection strings section.
ConnectionStringsSection csSection = config.ConnectionStrings;
// Add the new element.
//csSection.ConnectionStrings.Add(csSettings);
// Save the configuration file.
config.Save(ConfigurationSaveMode.Modified);
using (var northwindEntities = new NorthwindEntities())
{
Console.WriteLine(northwindEntities.Database.CreateIfNotExists());
}
}
private static void DeleteCustomer(string customerId)
{
using (var northwindEntities = new NorthwindEntities())
{
Customer customer = GetCustomerById(northwindEntities, customerId);
northwindEntities.Customers.Remove(customer);
northwindEntities.SaveChanges();
}
}
private static string CreateNewCustomer(string customerId, string companyName, string contactName)
{
using (var northwindEntities = new NorthwindEntities())
{
Customer newCustomer = new Customer
{
CustomerID = customerId,
CompanyName = companyName,
ContactName = contactName
};
northwindEntities.Customers.Add(newCustomer);
northwindEntities.SaveChanges();
return newCustomer.CustomerID;
}
}
public static void Main()
{
// 8.By inheriting the Employee entity class create a class which allows employees to access their corresponding territories as property of type EntitySet<T>.
// class EmployeeExtend in EntityFrameworkModels
using (var northwind = new NorthwindEntities())
{
var employee = northwind.Employees.Find(2);
foreach (var item in employee.TerritoryProperty)
{
Console.WriteLine("Employee:{0} Teritory desctiption: {1}", employee.FirstName, item.TerritoryDescription);
}
}
}
private static void FindAllCustomersWithOrdersFrom1997UsingSQL()
{
using (var northwindEntities = new NorthwindEntities())
{
string nativeSqlQuery =
"SELECT * FROM dbo.Orders o " +
"JOIN dbo.Customers c " +
"ON o.CustomerID = c.CustomerID " +
"WHERE (OrderDate BETWEEN '1997.01.01' AND '1997.12.31') AND ShipCountry = 'Canada' " +
"ORDER BY c.CompanyName";
var customers = northwindEntities.Database.SqlQuery<OrdersToCanada>(nativeSqlQuery);
foreach (var item in customers)
{
Console.WriteLine(string.Format("Company: {0}, CompanyContact: {1}", item.CompanyName, item.ContactName));
}
}
}
private static void FindAllSalesBySpecifiedRegionAndPeriod(string region, DateTime startDate, DateTime endDate)
{
using (var northwindEntities = new NorthwindEntities())
{
var sales = northwindEntities
.Order_Details
.Where(o => o.Order.ShipRegion == region)
.Where(o => o.Order.OrderDate >= startDate)
.Where(o => o.Order.OrderDate <= endDate)
.Select(c => new
{
Customer = c.Order.Customer.CompanyName,
Date = c.Order.OrderDate,
Product = c.Product.ProductName
})
.ToList();
foreach (var item in sales)
{
Console.WriteLine("Customer:{0} , OrderDate:{1}, Product:{2}", item.Customer, item.Date, item.Product);
}
}
}
private static void FindAllCustomersWithOrdersFrom1997()
{
using (var northwindEntities = new NorthwindEntities())
{
var customers = northwindEntities
.Orders
.Where(o => o.ShipCountry == "Canada")
.Where(o => o.OrderDate >= new DateTime(1997, 01, 01))
.Where(o => o.OrderDate <= new DateTime(1997, 12, 31))
.OrderBy(o => o.Customer.CompanyName)
.Select(e => new
{
Company = e.Customer.CompanyName,
ContactName = e.Customer.ContactName,
Country = e.ShipCountry
})
.ToList();
foreach (var item in customers)
{
Console.WriteLine(item);
}
}
}
private static void ModifyCustomerName(string customerId, string companyName, string contactName)
{
using (var northwindEntities = new NorthwindEntities())
{
Customer customer = GetCustomerById(northwindEntities, customerId);
customer.CompanyName = companyName;
customer.ContactName = contactName;
northwindEntities.SaveChanges();
}
}
private static Customer GetCustomerById(NorthwindEntities northwindEntities, string customerId)
{
Customer customer = northwindEntities
.Customers
.FirstOrDefault(
p => p.CustomerID == customerId);
return customer;
}
