LINQ Interview Question #51

What is a join in LINQ?

Joins, Grouping, Set & Quantifier Operators Mid-Level Intermediate

Quick Interview Answer

A join combines related elements from two data sources by matching keys. LINQ provides the Join operator for an inner join and GroupJoin for grouped relationships.

Detailed Explanation

A join combines related elements from two data sources by matching keys. LINQ provides the Join operator for an inner join and GroupJoin for grouped relationships.

Joins are useful when related data is stored in separate sequences or tables and the result needs values from both sources.

Code Example

var result = customers.Join(
    orders,
    customer => customer.Id,
    order => order.CustomerId,
    (customer, order) => new
    {
        customer.Name,
        order.Id,
        order.Total
    });