/// <summary>
/// https://docs.microsoft.com/en-us/ef/core/saving/transactions
/// </summary>
static void Transactions()
{
using (var db = new NWContext())
{
var tran = db.Database.BeginTransaction();
try
{
// Acciones
tran.Commit();
}
catch (Exception)
{
tran.Rollback();
throw;
}
}
using (var ts = new TransactionScope())
{
using (var db = new NWContext())
{
// CRUD actions
db.SaveChanges();
}
ts.Complete();
}
}
static void EagerLoading()
{
// Eager Loading
using (NWContext db = new NWContext())
{
// Proyección
var customersOrders =
from c in db.Customers.
OrderBy(c => c.CustomerId).
Skip(10).Take(2)
select new
{
Cliente = c,
Ordenes = c.Orders
};
foreach (var c in customersOrders)
{
Console.WriteLine($"{c.Cliente.CustomerId}, {c.Cliente.ContactName}");
foreach (var o in c.Ordenes)
{
Console.WriteLine($"{o.OrderId}, {o.OrderDate}");
}
}
var customersOrders2 = from c in db.Customers.
Include(c => c.Orders).
Include("Orders.OrderDetails").
OrderBy(c => c.CustomerId).
Skip(10).Take(2)
select c;
var customersOrders2x = db.Customers.
Include("Orders").
Include("CustomerDemographics").Take(2);
foreach (var c in customersOrders2)
{
Console.WriteLine($"{c.CustomerId}, {c.ContactName}");
foreach (var o in c.Orders)
{
Console.WriteLine($"{o.OrderId}, {o.OrderDate}");
foreach (var od in o.OrderDetails)
{
Console.WriteLine($"{od.ProductId}, {od.Quantity}");
}
}
}
}
}
static void Main(string[] args)
{
using (var db = new NWContext())
{
var query = db.Products.Where(p => p.ProductName.Contains("queso"));
//foreach (var p in db.Products)
foreach (var p in query)
{
Console.WriteLine($"{p.ProductId} {p.ProductName}");
}
}
Console.WriteLine("READY");
Console.ReadKey();
}
// https://dynamic-linq.net/
static void LINQDynamic()
{
// Ordenamiento
using (NWContext db = new NWContext())
{
string order = "Country DESC, City";
var q1 = db.Customers.Where(c => c.Orders.Count > 5).OrderBy(order);
Console.Clear();
foreach (var item in q1)
{
Console.WriteLine($"{item.CompanyName.PadRight(35)}, {item.Country}, {item.City}");
}
}
}
static void RawSQL()
{
using (var db = new NWContext())
{
// https://docs.microsoft.com/en-us/ef/core/querying/raw-sql
// Prior to version 3.0, FromSqlRaw and FromSqlInterpolated were two overloads named FromSql
//var q2 = db.Products.FromSql("",null)
var quantity = 12;
int productsTotal = db.Database.ExecuteSqlInterpolated($"update [Order Details] set Quantity = {quantity} where OrderID = 10248 and ProductID = 11");
var pQuantity = new SqlParameter("quantity", quantity);
int affected = db.Database.ExecuteSqlRaw("update [Order Details] set Quantity = @quantity where OrderID = 10248 and ProductID = 11", pQuantity);
var filter = 1;
var products0 = db.Products.FromSqlInterpolated(@$ "SELECT [ProductID],[ProductName],[SupplierID],[CategoryID]
,[QuantityPerUnit],[UnitPrice],[UnitsInStock],[UnitsOnOrder],[ReorderLevel],[Discontinued]
static void LINQToXML()
{
using (NWContext db = new NWContext())
{
List <Customers> customers = db.Customers.ToList();
// LINQ to Objects
var q1 = from c in customers
where c.Country == "Mexico"
select c;
var q1x = customers.Where(c => c.Country == "Mexico");
// LINQ to XML
var docXML = new XElement("customers",
from c in customers
select new XElement("customer",
new XElement("id", c.CustomerId),
new XElement("companyName", c.CompanyName),
new XElement("contactName", c.ContactName))
);
docXML.Save("customer.xml");
var docXML2 = XElement.Load("customer.xml");
var query = from c in docXML2.Descendants("customer")
where c.Element("companyName").Value.StartsWith("A", StringComparison.CurrentCulture)
select new Customers()
{
CustomerId = c.Element("id").Value,
CompanyName = c.Element("companyName").Value,
ContactName = c.Element("contactName").Value
};
foreach (var item in query)
{
Console.WriteLine(item.CompanyName);
}
}
}
private static void CRUD()
{
using (var db = new NWContext())
{
int lastId = db.Products.Max(p => p.ProductId);
var np = new Product()
{
ProductName = $"Demostración #{++lastId}",
Discontinued = false
};
db.Products.Add(np);
db.SaveChanges();
np.ProductName += " ACTUALIZADO";
foreach (var e in db.ChangeTracker.Entries <Product>())
{
Console.WriteLine($"{e.Property("ProductName").CurrentValue} {e.State}");
}
db.SaveChanges();
db.Products.Remove(np);
db.SaveChanges();
foreach (var p in db.Products.Include(p => p.Category))
{
Console.WriteLine($"{p.ProductId}, {p.ProductName}, {p.UnitPrice}, {p.Category?.CategoryName ?? "Sin categoría"}");
}
Console.WriteLine($"Total de productos: {db.Products.Count()}");
Console.ReadLine();
}
}
private static void Basic()
{
var builder = new ConfigurationBuilder()
.SetBasePath(Directory.GetCurrentDirectory())
.AddJsonFile("appsettings.json");
IConfigurationRoot configuration = builder.Build();
var optionsBuilder = new DbContextOptionsBuilder <NWContext>();
optionsBuilder.UseSqlServer(configuration.GetConnectionString("NW"));
//using (var db = new NWContext())
using (var db = new NWContext(optionsBuilder.Options))
{
// query
var q0 = from p in db.Products
where p.ProductName.Contains("queso")
select p;
var q1 = (from p in db.Products
where p.ProductName.Contains("queso")
select p).All(p => p.Discontinued);
// métodos de extensión + expresiones lambda
var query = db.Products.Where(p => p.ProductName.Contains("queso"));
bool discontinued = db.Products.All(p => p.Discontinued);
//foreach (var p in db.Products)
foreach (var p in query)
{
Console.WriteLine($"{p.ProductId} {p.ProductName}");
}
}
}
static void LazyLoading()
{
// Lazy Loading
using (NWContext db = new NWContext())
{
//bool isLazy = true;
//db.ChangeTracker.LazyLoadingEnabled = isLazy; // default = true
// .Include(c=>c.Orders). // Eager Loading
var customers = db.Customers.
OrderBy(c => c.CustomerId);
foreach (var c in customers.ToList())
{
Console.WriteLine($"{c.CustomerId}, {c.ContactName}");
//if (!isLazy)
//{
// db.Entry(c).Collection(o => o.Orders).Load();
//}
Console.WriteLine($"Número de Órdenes: {c.Orders.Count}");
}
foreach (var o in db.Orders)
{
//if (!isLazy)
//{
// db.Entry(o).Reference(c => c.Customer).Load();
//}
Console.WriteLine(o.Customer.ContactName);
Console.WriteLine($"{o.OrderId}, {o.OrderDate}");
}
}
}
static void LINQToEntities()
{
using (NWContext db = new NWContext())
{
// Filtro
var q1 = from c in db.Customers
where c.Country == "Mexico"
select c;
var q1x = db.Customers.
Where(c => c.Country == "Mexico");
//var result = q1.Count();
//var any = result.Any();
foreach (var item in q1x)
{
Console.WriteLine($"{item.CustomerId} {item.CompanyName} {item.ContactName} {item.Country}");
}
}
// Proyecciones
using (NWContext db = new NWContext())
{
var q2 = from c in db.Customers
select c.Country;
var q2x = db.Customers.Select(c => c.Country);
var q2y = from c in db.Customers
select new { c.CustomerId, c.ContactName };
var q2z = db.Customers.Select(c =>
new { Id = c.CustomerId, c.ContactName });
var q2w = db.Customers.Select(c =>
new Categories()
{
CategoryName = c.ContactName
});
Console.Clear();
foreach (var item in q2z)
{
Console.WriteLine($"{item.Id}, {item.ContactName}");
}
}
// SelectMany
using (NWContext db = new NWContext())
{
var q4 = db.Customers.
Where(c => c.Country == "Mexico").
SelectMany(c => c.Orders);
var q4x = db.Orders.
Where(o => o.Customer.Country == "Mexico");
Console.Clear();
foreach (var item in q4)
{
Console.WriteLine($"{item.CustomerId}, {item.OrderId}");
}
}
// Ordenamiento
using (NWContext db = new NWContext())
{
var q5 = from c in db.Customers
where c.Orders.Count > 5
orderby c.Country descending
select c;
var q5x = db.Customers.
Where(c => c.Orders.Count > 5).
OrderByDescending(c => c.Country);
Console.Clear();
foreach (var item in q5)
{
Console.WriteLine($"{item.CompanyName}, {item.Country}");
}
var q6 = from c in db.Customers
orderby c.CompanyName, c.ContactTitle,
c.ContactName
select c;
var q6x = db.Customers.OrderBy(c =>
new
{
c.CompanyName,
c.ContactTitle
}).
ThenBy(c => c.ContactName);
Console.Clear();
foreach (var item in q6)
{
Console.WriteLine($"{item.CompanyName}, {item.Country}");
}
}
// Agrupamiento
using (NWContext db = new NWContext())
{
var q7 = from c in db.Customers
group c by c.Country into CustByCountry
select CustByCountry;
var q7x = db.Customers.GroupBy(c => c.Country);
Console.Clear();
foreach (var item in q7)
{
Console.WriteLine($"{item.Key}, {item.Count()}");
foreach (var c in item)
{
Console.WriteLine($"\t{c.ContactName}");
}
}
var q7y = from c in db.Customers
group c by new { c.Country, c.City } into CountryCity
where CountryCity.Count() > 1
select new
{
Country = CountryCity.Key.Country,
City = CountryCity.Key.City,
Count = CountryCity.Count(),
Items = CountryCity
};
var q7y2 = db.Customers.GroupBy(c => new { c.Country, c.City }).
Where(g => g.Count() > 1).
Select(g => new
{
Country = g.Key.Country,
City = g.Key.City,
Count = g.Count(),
Items = g
});
Console.Clear();
foreach (var item in q7y)
{
Console.WriteLine($"{item.Country}, {item.City}, {item.Count}");
foreach (var c in item.Items)
{
Console.WriteLine($"\t{c.ContactName}");
}
}
}
// Join
using (NWContext db = new NWContext())
{
var q8 = from c in db.Customers
join o in db.Orders on c.CustomerId
equals o.CustomerId
select new { c, o };
// new { c.CustomerID, c.Country }
//equals new { o.CustomerID, Country = o.ShipCountry }
var q8x = db.Customers.Join(
db.Orders, c => c.CustomerId,
o => o.CustomerId,
(c, o) => new { c, o });
Console.Clear();
foreach (var item in q8)
{
Console.WriteLine($"{item.c.CustomerId}, {item.o.OrderId}");
}
// Join agrupado
var q8y = from c in db.Customers
join o in db.Orders on c.CustomerId
equals o.CustomerId into CustomerOrders
select new { c, Orders = CustomerOrders };
//select CustomerOrders;
foreach (var ordenes in q8y)
{
//foreach (var orden in ordenes)
//{
//}
}
// Left Ourter Join
var q8z = from c in db.Customers
join o in db.Orders on c.CustomerId
equals o.CustomerId into CustomerOrders
from detalle in CustomerOrders.DefaultIfEmpty()
select new
{
Customer = c,
Order = detalle
};
foreach (var item in q8z)
{
if (item.Order == null)
{
Console.WriteLine($"Customer {item.Customer.CustomerId} with NO orders!");
}
}
}
// Conjuntos
using (NWContext db = new NWContext())
{
var q9 = db.Customers.
Select(c => c.Country).Distinct();
var q10 = db.Customers.Except(
db.Customers.Where(
c => c.Country == "Mexico")).
Select(c => c.Country).Distinct();
Console.Clear();
foreach (var item in q10)
{
Console.WriteLine($"{item}");
}
}
// Partición (paginación)
using (NWContext db = new NWContext())
{
var q11 = db.Customers.
OrderBy(c => c.CustomerId).
Skip(10);
// Tomar los primero 10 elementos
var q12 = db.Customers.
OrderBy(c => c.CustomerId).
Take(10);
// Segunda página de 10 elementos
var q13 = db.Customers.
OrderBy(c => c.CustomerId).
Skip(10).Take(10);
Console.Clear();
foreach (var item in q13)
{
Console.WriteLine($"{item.CustomerId}, {item.CompanyName}");
}
}
// Modificación de consulta
using (NWContext db = new NWContext())
{
var q14 = db.Customers.
Where(c => c.Orders.Count > 5);
Console.Clear();
Console.WriteLine(q14.Count());
q14 = q14.Where(c => c.Country == "Mexico");
Console.WriteLine(q14.Count());
q14 = q14.OrderByDescending(c => c.ContactName);
foreach (var item in q14)
{
Console.WriteLine(item.ContactName);
}
}
// Métodos útiles
using (NWContext db = new NWContext())
{
var o1 = db.Customers.First();
o1 = db.Customers.FirstOrDefault();
o1 = db.Customers.Where(c => c.CustomerId == "ALFKI")
.Single();
o1 = db.Customers.Where(c => c.CustomerId == "ALFKI").
SingleOrDefault();
var o2 = db.Customers.All(c => c.Orders.Count > 5 &&
c.Country == "Mexico");
o2 = db.Customers.
Any(c => c.Orders.Count > 5);
var sum = db.OrderDetails.
Sum(od => od.Quantity * od.UnitPrice);
}
}