LINQ: A simple introduction

Transcript

1. LINQ: A simple Introduction Fanie Reynders Technical Team Lead @FanieReynders
2. Agenda What is LINQ? LINQ Queries Examples Exploring a LINQ to * scenario
3. What is LINQ? LINQ (pronounced "link") - Language Integrated Query Microsoft .NET Framework component Extends powerful query capabilities to the language syntax in .NET Introduces standard, easily-learned patterns for querying and updating data Extendable
4. LINQ Queries: Overview 3 parts of a LINQ Query: // 1. Data source. int[] numbers = new int[7] { 0, 1, 2, 3, 4, 5, 6 }; // 2. Query creation. // numQuery is an IEnumerable<int> var numQuery = from num in numbers where (num % 2) == 0 select num; // 3. Query execution. foreach (int num in numQuery) { Console.Write("{0,1} ", num); }
5. LINQ Queries: Query operation Data source Query from... where... select... Execution foreach (int item in ) Query Return each item item Do something with item … Get next item
6. LINQ Queries: Data sources In memory o IEnumerable o IList o Array (or []) o ICollection Derived on-demand o IQueryable
7. LINQ Queries: Query structure From Join Group Where OrderBy Select
8. LINQ Queries: Comparison with SQL SELECT * FROM People AS p WHERE p.City = 'Johannesburg' ORDER BY p.Surname from p in People where p.City == "Johannesburg" orderby p.Surname select p; LINQ Query: SQL Query:
9. LINQ Queries: Using Lambdas var joburgPeople = from p in People where p.City == "Johannesburg" orderby p.Surname select p; Using Lamda Expressions: var joburgPeople = People.Where(p => p.City == "Johannesburg") .OrderBy(p => p.Surname) .Select(p => p);
10. Demo Time! #hopeitworks
11. LINQ to * Amazon Active Directory CSV Datasets Entities Excel Facebook Files Google Oracle RegEx SQL Twitter XML etc…
12. LINQ to *: Case study For the stock code “MSFT” we need to search Facebook for the people who likes it as well as Twitter for the followers of Microsoft, then combine it with all our customers under the age of 55 that lives in any of our operational areas including the latest price from NASDAQ. This information need to be merged, ordered by surname and grouped by age. We need to export it to an Excel Spreadsheet.
13. LINQ to *: Possibilities Facebook Twitter NASDAQ SQL XML Excel 1 1 1 3 2
14. Demo Time! Thank you