static void LinqInnerJoin()
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var innerJoin =
from p in MyProduct.GetProducts()
join c in MyCategory.GetCategories() on p.CategoryId equals c.CategoryId
select new { p.ProductName, c.CategoryName };
// Fluent expression equivalent.
// var innerJoin = MyProduct.GetProducts().Join(MyCategory.GetCategories(), p => p.CategoryId, c => c.CategoryId, (p, c) => new { p.ProductName, c.CategoryName });
Console.WriteLine("Inner join:");
foreach (var v in innerJoin)
{
Console.WriteLine(v);
}
}
static void LinqCrossJoin()
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var crossJoin =
from p in MyProduct.GetProducts()
from c in MyCategory.GetCategories()
select new { p.ProductName, c.CategoryName };
// Fluent expression equivalent.
// var crossJoin = MyProduct.GetProducts().SelectMany(p => MyCategory.GetCategories().Select(c => new { p.ProductName, c.CategoryName }));
Console.WriteLine("Cross join:");
foreach (var v in crossJoin)
{
Console.WriteLine(v);
}
}
static void LinqGroupJoin2()
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var groupJoin =
from c in MyCategory.GetCategories()
join p in MyProduct.GetProducts() on c.CategoryId equals p.CategoryId into pc
from prod in pc
select new { c.CategoryName, prod.ProductName };
// Fluent expression equivalent.
// var groupJoin = MyCategory.GetCategories().GroupJoin(MyProduct.GetProducts(), c => c.CategoryId, p => p.CategoryId, (c, ps) => new { c.CategoryName, Products = ps }).SelectMany(tmp => tmp.Products, (tmp, prod) => new { tmp.CategoryName, prod.ProductName });
Console.WriteLine("Group join with flat collection:");
foreach (var v in groupJoin)
{
Console.WriteLine(v.CategoryName + " - " + v.ProductName);
}
}
static void LinqRightOuterJoin()
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var rightOuterJoin =
from c in MyCategory.GetCategories()
join p in MyProduct.GetProducts() on c.CategoryId equals p.CategoryId into pc
from prod in pc.DefaultIfEmpty(MyProduct.Empty)
select new { prod.ProductName, c.CategoryName };
// Fluent expression equivalent.
// var rightOuterJoin = MyCategory.GetCategories().GroupJoin(MyProduct.GetProducts(), c => c.CategoryId, p => p.CategoryId, (c, ps) => new { Products = ps, c.CategoryName }).SelectMany(tmp => tmp.Products.DefaultIfEmpty(MyProduct.Empty), (tmp, prod) => new { prod.ProductName, tmp.CategoryName });
Console.WriteLine("Right outer join:");
foreach (var v in rightOuterJoin)
{
Console.WriteLine(v);
}
}
static void LinqLeftOuterJoin()
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var leftOuterJoin =
from p in MyProduct.GetProducts()
join c in MyCategory.GetCategories() on p.CategoryId equals c.CategoryId into pc
from cat in pc.DefaultIfEmpty(MyCategory.Empty)
select new { p.ProductName, cat.CategoryName };
// Fluent expression equivalent.
// var leftOuterJoin = MyProduct.GetProducts().GroupJoin(MyCategory.GetCategories(), p => p.CategoryId, c => c.CategoryId, (p, cs) => new { p.ProductName, Categories = cs }).SelectMany(tmp => tmp.Categories.DefaultIfEmpty(MyCategory.Empty), (tmp, cat) => new { tmp.ProductName, cat.CategoryName });
Console.WriteLine("Left outer join:");
foreach (var v in leftOuterJoin)
{
Console.WriteLine(v);
}
}
static void LinqGroupJoin1()
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
/*
* var groupJoin =
* from c in MyCategory.GetCategories()
* join p in MyProduct.GetProducts() on c.CategoryId equals p.CategoryId into pc
* select new { c.CategoryName, Products = pc };
*/
// Fluent expression equivalent.
var groupJoin = MyCategory.GetCategories().GroupJoin(MyProduct.GetProducts(), c => c.CategoryId, p => p.CategoryId, (c, ps) => new { c.CategoryName, Products = ps });
Console.WriteLine("Group join:");
foreach (var c in groupJoin)
{
Console.WriteLine(" Category: " + c.CategoryName);
foreach (var p in c.Products)
{
Console.WriteLine(" " + p.ProductName);
}
}
}
static void LinqFullOuterJoin()
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var fullOuterJoin = (
from p in MyProduct.GetProducts()
join c in MyCategory.GetCategories() on p.CategoryId equals c.CategoryId into pc
from cat in pc.DefaultIfEmpty(MyCategory.Empty)
select new { p.ProductName, cat.CategoryName }).Union(
from c in MyCategory.GetCategories()
join p in MyProduct.GetProducts() on c.CategoryId equals p.CategoryId into pc
from prod in pc.DefaultIfEmpty(MyProduct.Empty)
select new { prod.ProductName, c.CategoryName });
// Fluent expression equivalent.
// var fullOuterJoin = (MyProduct.GetProducts().GroupJoin(MyCategory.GetCategories(), p => p.CategoryId, c => c.CategoryId, (p, cs) => new { p.ProductName, Categories = cs }).SelectMany(tmp => tmp.Categories.DefaultIfEmpty(MyCategory.Empty), (tmp, cat) => new { tmp.ProductName, cat.CategoryName })).Union(
// MyCategory.GetCategories().GroupJoin(MyProduct.GetProducts(), c => c.CategoryId, p => p.CategoryId, (c, ps) => new { Products = ps, c.CategoryName }).SelectMany(tmp => tmp.Products.DefaultIfEmpty(MyProduct.Empty), (tmp, prod) => new { prod.ProductName, tmp.CategoryName }));
Console.WriteLine("Full outer join:");
foreach (var v in fullOuterJoin)
{
Console.WriteLine(v);
}
}