LINQ for absolute beginners
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This document provides an introduction to LINQ (Language Integrated Query) for querying and manipulating data from different data sources. It discusses some key LINQ concepts and operators including projection, restriction, grouping, aggregation, and ordering. It also provides sample LINQ queries against a sample data source and compares the syntax to equivalent SQL queries. The document explains the different types of query execution in LINQ and provides additional resources for learning more.
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LINQ for absolute beginners
- 1. LINQ (Language Integrated Query) for absolute beginner Vasistan Shakkaravarthi 1
- 2. Introduction • A query is an expression that retrieves data from a data source. • Queries are usually expressed in a specialized query language. • Different languages have been developed over time for the various types of data sources, for example • SQL for relational databases • XQuery for XML. 2LINQ for absolute beginners
- 4. Frequently used Operators Projection Select Select Many Restriction Where Grouping GroupBy Aggregate Sum Count Min Max Average Ordering OrderBy OrderByDescending ThenBy ThenByDescending Reverse 4LINQ for absolute beginners
- 5. Steps involved in LINQ operation Obtain the Data Source Create Query Execute 5LINQ for absolute beginners
- 6. Sample data source EmpID EmpName Gender Age ShortCode 1 Kathirvel M 26 KV 2 Vivian M 27 OV 3 Veeramanai M 25 AV 4 Kalpana F 26 KL 5 Kavitha F 25 KS 6 Vasi M 28 SV 7 Kamalam F 28 KL 8 Sudha F 27 SS 9 Kumaraguru M 28 KG 6LINQ for absolute beginners
- 7. Projection Operator SELECT e.EmpName FROM EmployeeInfo e from e in EmployeeInfo select e.EmpName SQL LINQ Select SELECT e.EmpName, e.Age FROM EmployeeInfo e from e in EmployeeInfo select new {EmpName = e.EmpName, Age = e.Age } SQL LINQ SelectMany EmpName Kathirvel Vivian Veeramanai Kalpana Kavitha Vasi Kamalam Sudha Kumaraguru EmpName Age Kathirvel 26 Vivian 27 Veeramanai 25 Kalpana 26 Kavitha 25 Vasi 28 Kamalam 28 Sudha 27 Kumaraguru 28 7LINQ for absolute beginners
- 8. Restriction Operators SELECT e.EmpName FROM EmployeeInfo e WHERE e.Gender = ‘M’ from e in EmployeeInfo where e.Gender == ‘M’ select e.EmpName SQL LINQ Where EmpName Kathirvel Vivian Veeramanai Vasi Kumaraguru 8LINQ for absolute beginners
- 9. Grouping/Aggregate Operators SELECT e.Gender, Count(e.*) as Employees FROM EmployeeInfo e GROUP BY e.Gender from e in EmployeeInfo group e by e.Gender into grp select new {Gender = e.Key, Employees = grp.Count()} SQL LINQ Grouping/ Aggregation Gender Employees F 4 M 5 9LINQ for absolute beginners
- 10. Ordering Operators SELECT e.EmpName FROM EmployeeInfo e ORDER BY e.EmpName from e in EmployeeInfo orderby e.EmpName select e.EmpName SQL LINQ OrderBy 10LINQ for absolute beginners EmpName Kalpana Kamalam Kathirvel Kavitha Kumaraguru Sudha Vasi Veeramanai Vivian from e in EmployeeInfo orderby e.EmpName descending select e.EmpName OrderByDescending EmpName Vivian Veeramanai Vasi Sudha Kumaraguru Kavitha Kathirvel Kamalam Kalpana
- 11. Query Execution Types • Simple query for further operation Deferred Query • Query that involves aggregate functions Immediate Query LINQ for absolute beginners 11
- 12. Thank you Check the other resources Blog http://vasistan.blogspot.in YouTube http://www.youtube.com/playlist?list=PL-CcORxeaUcgXHO7UW9sGNbue9wH-4No3