Join Customers and Orders
Combine related sequences with LINQ Join.
Introduction
Join matches keys across two typed collections much like a relational database join.
The key selectors choose CustomerId from each sequence and the result selector shapes each match.
Runnable C# example
Program.cs
using System;
using System.Linq;
record Customer(int Id, string Name);
record Order(int CustomerId, decimal Total);
class Program
{
static void Main()
{
var customers = new[] { new Customer(1, "Ada"), new Customer(2, "Lin") };
var orders = new[] { new Order(2, 40m), new Order(1, 25m) };
var rows = customers.Join(orders, c => c.Id, o => o.CustomerId, (c, o) => $"{c.Name}: {o.Total}");
Console.WriteLine(string.Join(" | ", rows));
}
}
Ada: 25 | Lin: 40Practice with the debugger
Set a breakpoint on an important assignment or condition, click Debug, and inspect the local values before stepping to the next line.
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