static void Main(string [] args)
{
using var db = new Northwind();
var query = db.Products
.Where(product => product.UnitPrice < 10M)
.OrderByDescending(product => product.UnitPrice)
.Select(product => new
{
product.ProductID,
product.ProductName,
product.UnitPrice
});
WriteLine("Products that cost less than $10:");
foreach (var item in query)
{
WriteLine($"{item.ProductID}: {item.ProductName} costs {item.UnitPrice:$#,##0.00}");
}
WriteLine();
WriteLine("Print the joining of the Categories and Products records...");
// create two sequences that we want to join together
var categories = db.Categories
.Select(c => new { c.CategoryID, c.CategoryName }).ToArray();
var products = db.Products.Select(p => new
{
p.ProductID, p.ProductName, p.CategoryID
}).ToArray();
// Join every product to its category to return 77 matches
var queryJoin = categories.Join(products,
category => category.CategoryID,
product => product.CategoryID,
(c, p) => new
{
c.CategoryName, p.ProductName, p.ProductID
});
foreach (var item in queryJoin)
{
WriteLine($"{item.ProductID}: {item.ProductName} is in {item.CategoryName}");
}
WriteLine("\nGrouping products by their Categories");
// group all products by their category to return 8 matches
var queryGroup = categories.GroupJoin(products,
category => category.CategoryID,
product => product.CategoryID,
(c, products) => new
{
c.CategoryName,
products = products.OrderBy(p => p.ProductName)
});
foreach (var item in queryGroup)
{
WriteLine($"{item.CategoryName} has {item.products.Count ()} products.");
foreach (var product in item.products)
{
WriteLine($" {product.ProductName}");
}
}
WriteLine("Products");
WriteLine($" Count: {db.Products.Count ()}");
WriteLine($" Sum of units in stock: {db.Products.Sum ( p => p.UnitsInStock ):N0}");
WriteLine($" Sum of units on order: {db.Products.Sum ( p => p.UnitsOnOrder ): N0}");
WriteLine($" Average unit price: {db.Products.Average ( p => p.UnitPrice ):$#,##0.00}");
WriteLine(
$" Value of units in stock: {db.Products.Sum ( p => p.UnitPrice * p.UnitsInStock ):$#,##0.00}");
WriteLine("\nTime for some query comprehension syntax...");
var names = new string [] { "Michael", "Pam", "Jim", "Dwight", "Angela", "Kevin", "Toby", "Creed" };
var namesQuery = from name in names
where name.Length > 4
orderby name.Length, name
select name;
foreach (var name in namesQuery)
{
WriteLine($"{name}");
}
var myqLinqQuery = db.Products
.ProcessSequence()
.Where(product => product.UnitPrice < 10M)
.OrderByDescending(product => product.UnitPrice)
.Select(product => new
{
product.ProductID,
product.ProductName,
product.UnitPrice
});
WriteLine("Custom LINQ extension methods:");
WriteLine($"Mean units in stock: {db.Products.Average ( p => p.UnitsInStock ):N0}");
WriteLine($"Mean unit price: {db.Products.Average ( p => p.UnitPrice ):$#,##0.00)}");
WriteLine($" Median units in stock: {db.Products.Median ( p => p.UnitsInStock )}");
WriteLine($" Median unit price: {db.Products.Median ( p => p.UnitPrice ):$#,##0.00}");
WriteLine($" Mode units in stock: {db.Products.Mode ( p => p.UnitsInStock )}");
WriteLine($" Mode units price: {db.Products.Mode ( p => p.UnitPrice ):$#,##0.00}");
var productsForXml = db.Products.ToArray();
var xml = new XElement("products",
from p in productsForXml
select new XElement("product",
new XAttribute("id", p.ProductID),
new XAttribute("price", p.UnitPrice),
new XElement("name", p.ProductName)));
WriteLine(xml.ToString());
XDocument doc = XDocument.Load("settings.xml");
var appSettings = doc.Descendants("appSettings")
.Descendants("add").Select(node => new
{
Key = node.Attribute("key").Value,
Value = node.Attribute("value").Value
}).ToArray();
foreach (var item in appSettings)
{
WriteLine($"{item.Key}: {item.Value}");
}
static void Main(string[] args)
{
using (var db = new Northwind())
{
var query = db.Products
.ProcessSequence()
.Where(product => product.UnitPrice < 10M)
.OrderByDescending(product => product.UnitPrice)
.Select(product => new
{
product.ProductID,
product.ProductName,
product.UnitPrice
});
WriteLine("Products that cost less than $10:");
foreach (var item in query)
{
WriteLine($"{item.ProductID}: {item.ProductName} costs {item.UnitPrice:$#,##0.00}");
}
WriteLine();
// create two sequences that we want to join together
var categories = db.Categories.Select(
c => new { c.CategoryID, c.CategoryName }).ToArray();
var products = db.Products.Select(
p => new { p.ProductID, p.ProductName, p.CategoryID }).ToArray();
// join every product to its category to return 77 matches
var queryJoin = categories.Join(products,
category => category.CategoryID,
product => product.CategoryID,
(c, p) => new { c.CategoryName, p.ProductName, p.ProductID })
.OrderBy(cp => cp.ProductID);;
foreach (var item in queryJoin)
{
WriteLine($"{item.ProductID}: {item.ProductName} is in {item.CategoryName}.");
}
// group all products by their category to return 8 matches
var queryGroup = categories.GroupJoin(products,
category => category.CategoryID,
product => product.CategoryID,
(c, Products) => new
{
c.CategoryName,
Products = Products.OrderBy(p => p.ProductName)
});
foreach (var item in queryGroup)
{
WriteLine(
$"{item.CategoryName} has {item.Products.Count()} products.");
foreach (var product in item.Products)
{
WriteLine($" {product.ProductName}");
}
}
WriteLine("Products");
WriteLine($" Count: {db.Products.Count()}");
WriteLine($" Sum of units in stock: {db.Products.Sum(p => p.UnitsInStock):N0}");
WriteLine($" Sum of units on order: {db.Products.Sum(p => p.UnitsOnOrder):N0}");
WriteLine($" Average unit price: {db.Products.Average(p => p.UnitPrice):$#,##0.00}");
WriteLine($" Value of units in stock: {db.Products.Sum(p => p.UnitPrice * p.UnitsInStock):$#,##0.00}");
WriteLine("Custom LINQ extension methods:");
WriteLine($" Mean units in stock: {db.Products.Average(p => p.UnitsInStock):N0}");
WriteLine($" Mean unit price: {db.Products.Average(p => p.UnitPrice):$#,##0.00}");
WriteLine($" Median units in stock: {db.Products.Median(p => p.UnitsInStock)}");
WriteLine($" Median unit price: {db.Products.Median(p => p.UnitPrice):$#,##0.00}");
WriteLine($" Mode units in stock: {db.Products.Mode(p => p.UnitsInStock)}");
WriteLine($" Mode unit price: {db.Products.Mode(p => p.UnitPrice):$#,##0.00}");
var productsForXml = db.Products.ToArray();
var xml = new XElement("products",
from p in productsForXml
select new XElement("product",
new XAttribute("id", p.ProductID),
new XAttribute("price", p.UnitPrice),
new XElement("name", p.ProductName)));
WriteLine(xml.ToString());
XDocument doc = XDocument.Load("settings.xml");
var appSettings = doc.Descendants(
"appSettings").Descendants("add")
.Select(node => new
{
Key = node.Attribute("key").Value,
Value = node.Attribute("value").Value
})
.ToArray();
foreach (var item in appSettings)
{
WriteLine($"{item.Key}: {item.Value}");
}
}
}
static void Main(string[] args)
{
using (var db = new Northwind()){
var querry = db.Products
.Where(product => product.UnitPrice < 10M)
.OrderByDescending(product => product.UnitPrice)
.Select(product => new {
product.ProductID,
product.ProductName,
product.UnitPrice
});
Console.WriteLine("Products that cost less than $10: ");
foreach (var item in querry)
{
Console.WriteLine($"{item.ProductID}: {item.ProductName} cost {item.UnitPrice:$#,##0.00}");
var categories = db.Categories.Select(c => new{
c.CategoryID,
c.CategoryName
}).ToArray();
var products = db.Products.Select(p => new{
p.ProductID,
p.ProductName,
p.CategoryID
}).ToArray();
var querryJoin = categories.Join(products
, cat => cat.CategoryID
, pr => pr.CategoryID
, (c, p) => new {
c.CategoryName,
p.ProductID,
p.ProductName
}).OrderBy(p => p.ProductID);
foreach (var i in querryJoin)
{
Console.WriteLine($"{i.ProductID}: {i.ProductName} is in {i.CategoryName}");
}
var querryGroup = categories.GroupJoin(products
, cat => cat.CategoryID
, pr => pr.CategoryID
, (c, Products) => new{
c.CategoryName,
Products = Products.OrderBy(p => p.ProductName)
});
Console.WriteLine("Group Join:");
foreach (var x in querryGroup)
{
Console.WriteLine($"{x.CategoryName} has {x.Products.Count()} products.");
foreach (var p in x.Products)
{
Console.WriteLine($" {p.ProductName}");
}
}
Console.WriteLine("Products:");
Console.WriteLine($"Count: {db.Products.Count()}");
Console.WriteLine($"Sum of units in stock: {db.Products.Sum(p => p.UnitsInStock):NO}");
Console.WriteLine($"SUm of units in order: {db.Products.Sum(p => p.UnitsOnOrder):NO}");
Console.WriteLine($"Average Unit Price: {db.Products.Average(p => p.UnitPrice):N0}");
Console.WriteLine($"Value of units in stock: {db.Products.Sum(p => p.UnitPrice * p.UnitsInStock):$#,##0.00}");
var productsForXml = db.Products.ToArray();
var xml = new XElement("products", from p in productsForXml
select new XElement("product",
new XAttribute("id", p.ProductID)
, new XAttribute("price", p.UnitPrice)
, new XElement("name", p.ProductName)
));
Console.WriteLine(xml.ToString());
XDocument doc = XDocument.Load("settings.xml");
var appSetting = doc.Descendants("appSettings").Descendants("add")
.Where(p => p.Attribute("key").Value == "color")
.Select(node => new {
Key = node.Attribute("key").Value,
Value = node.Attribute("value").Value
}).ToArray();
foreach (var el in appSetting)
{
Console.WriteLine($"{el.Key}: {el.Value}");
}
}
}
}
static void Main(string[] args)
{
using (var db = new Northwind())
{
var query = db.Products
.ProcessSequence()
.Where(product => product.UnitPrice < 10M)
.OrderByDescending(product => product.UnitPrice)
.Select(product => new
{
product.ProductID,
product.ProductName,
product.UnitPrice
});
WriteLine("Products that cost less than $10:");
foreach (var item in query)
{
WriteLine($"{item.ProductID}: {item.ProductName} costs {item.UnitPrice:$#,##0.00}");
}
WriteLine();
// создаем две последовательности, которые хотим присоединить
var categories = db.Categories.Select(c => new { c.CategoryID, c.CategoryName }).ToArray();
var products = db.Products.Select(
p => new {
p.ProductID,
p.ProductName,
p.CategoryID
}).ToArray();
// присоединяем каждый товар к своей категории, чтобы вернуть 77 совпадений
var queryJoin = categories.Join(products, category => category.CategoryID, product => product.CategoryID, (c, p) => new {
c.CategoryName,
p.ProductName,
p.ProductID
}).OrderBy(cp => cp.ProductID);
foreach (var item in queryJoin)
{
WriteLine($"{item.ProductID}: {item.ProductName} is in { item.CategoryName}.");
}
// группируем все товары по соответствующим категориям,
// чтобы вернуть восемь совпадений
var queryGroup = categories.GroupJoin(products, category => category.CategoryID, product => product.CategoryID, (c, Products) => new
{
c.CategoryName,
Products = Products.OrderBy(p => p.ProductName)
});
foreach (var item in queryGroup)
{
WriteLine($"{item.CategoryName} has { item.Products.Count()} products.");
foreach (var product in item.Products)
{
WriteLine($" {product.ProductName}");
}
}
WriteLine("Products");
WriteLine($" Count: {db.Products.Count()}");
WriteLine($" Sum of units in stock: {db.Products.Sum(p => p.UnitsInStock):N0}");
WriteLine($" Sum of units on order: {db.Products.Sum(p => p.UnitsOnOrder):N0}");
WriteLine($" Average unit price: {db.Products.Average(p => p.UnitPrice):$#,##0.00}");
WriteLine($" Value of units in stock: {db.Products.Sum(p => p.UnitPrice * p.UnitsInStock):$#,##0.00}");
WriteLine("Custom LINQ extension methods:");
WriteLine($" Mean units in stock: {db.Products.Average(p => p.UnitsInStock):N0}");
WriteLine($" Mean unit price: {db.Products.Average(p => p.UnitPrice):$#,##0.00}");
WriteLine($" Median units in stock: {db.Products.Median(p => p.UnitsInStock)}");
WriteLine($" Median unit price: {db.Products.Median(p => p.UnitPrice):$#,##0.00}");
WriteLine($" Mode units in stock: {db.Products.Mode(p => p.UnitsInStock)}");
WriteLine($" Mode unit price: {db.Products.Mode(p => p.UnitPrice):$#,##0.00}");
var productsForXml = db.Products.ToArray();
var xml = new XElement("products",
from p in productsForXml
select new XElement("product",
new XAttribute("id", p.ProductID),
new XAttribute("price", p.UnitPrice),
new XElement("name", p.ProductName)));
WriteLine(xml.ToString());
XDocument doc = XDocument.Load("settings.xml");
var appSettings = doc
.Descendants("appSettings")
.Descendants("add").Select(node => new
{
Key = node.Attribute("key").Value,
Value = node.Attribute("value").Value
}).ToArray();
foreach (var item in appSettings)
{
WriteLine($"{item.Key}: {item.Value}");
}
}
}