Linq-to-Entities Query. Here, you will learn how to write LINQ-to-Entities queries and get the result in Entity Framework 6.x as well as in Entity Framework Core. Visit LINQ Tutorials to learn LINQ step by step. The DbSet class is derived from IQuerayable. So, we can use LINQ for querying against DbSet, which will be converted to an SQL query. The LINQ family of technologies provides a consistent query experience for objects (LINQ to Objects), relational databases (LINQ to SQL), and XML (LINQ to XML). For a developer who writes queries, the most visible 'language-integrated' part of LINQ is the query expression. Query expressions are written in a declarative query syntax. Translating SQL to LINQ can prove difficult for new and experienced C# developers. This post contains common SQL queries written in LINQ. I hope it’ll serve as a reference when writing LINQ queries. I’ll use a MS SQL database and Entity Framework for my examples. However, these examples can be extracted to other ORMs and databases. LINQ to SQL Cheat Sheet in PDF form, containing both C# and VB.NET syntax. Improve this answer. Follow edited Feb 23 '10 at 21:13. 15.8k 8 8 gold badges 48 48 silver badges 97 97 bronze badges. Answered Feb 23 '10 at 21:10. Anthony Forloney Anthony Forloney.
just saw in my feed reader..a cheat sheet by keith rull for LINQ. keith purports that this isn't a definitive list by any means but says:
'It consist of a few snippets that you might commonly do when doing LINQ processing.'
he uses this for his most common tasks. when i first start learning anything new, i do the same thing keeping snippets around to help me remember certain things. as an example, can't remember how to do the paging? use keith's cheat:
thanks for posting keith and look forward to your updates!
Summary
A quick cheat-sheet to help write LINQ code.
LINQ Basics
- LINQ is an acronym for Language Integrated Query
- Consists of three basic operations: Get the source data, Create the query expression and execute the query.
- LINQ works on collections only and not on the database like SQL.
- Requires the assembly using System.Linq
- Returns the type IEnumerable making it possible to use the foreach loop.
LINQ Standard Query Operators
LINQ Anatomy
Define the source
Define the query expression
Execute the query
Full code implementation
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EXPLANATION:
var – the var keyword is used to return a datatype that is unknown. Var is an anonymous type and is often used when the return type is unknown or the return type is also anonymous.
getNumbers – this is the name of the query.
C# Cheatsheet 2020
from – this is a keyword which tells the compiler to retrieve data from a source.
number – this is the iterating variable. This is not a keyword therefore, this can be called anything. The iterating keyword is often shortened to a single character like ‘n‘.
in numbers – this tells the compiler to return data from our collection numbers.
C# Linq Cheat Sheet
where number < 5 – tells the compiler to return all numbers that are less than 5.
select number – this tells the compiler to select everything that has been returned in the query getNumbers.
Examples
Single where condition (integer)
Single where condition (string)
Multiple where conditions
The above can also be written as:
Orderby
Linq Standard Query Operators Cheat Sheet
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