Linq

Key Words

• Filter
  • from
  • in
  • where
• Order
  • orderby
  • descending
  • ascending
• Projecting
  • select
• Join
  • join
  • in
  • on
• Group
  • group
  • by
  • into
• Aggregate
  • Aggregate
• Others
  • equals
  • let
• Most userful
  • from * in * where * select *

Examples

var innerJoinQuery =
            from category in categories
            join prod in products on category.ID equals prod.CategoryID
            select new { ProductName = prod.Name, Category = category.Name };

var earlyBirdQuery =
            from sentence in strings
            let words = sentence.Split(' ')
            from word in words
            let w = word.ToLower() //How to use "let"
            where w[0] == 'a' || w[0] == 'e'
                || w[0] == 'i' || w[0] == 'o'
                || w[0] == 'u'
            select word;

Demo

Requirement: Get ranks of student by credit and score.

• Linq to CSV
• Linq to XML
  • xdocument
    
  • xdocument & xmldocument
  • xnamespace
• Linq to EF
  • IQueryable & IEnumerable