Skip to main content

LINQ - Deferred Execution

Deferred Execution means that queries are not executed immediately at the time it's being created. The benefit of this is to improve performance by avoiding unnecessary executions. It also allows the query to be extendable when needed such as sorting, filtering.

In the example below, the queries to retrieve courses are not being executed yet

var context = new DbContext();
var courses = context.Courses
    .Where(c => c.Level == 1)
    .OrderBy(c => c.Name);

The query is only executed when one of the following scenarios occurs:

  • Iterating over query variable
  • Calling ToList, ToArray, ToDictionary
  • Calling First, Last, Single, Count, Max, Min, Average

For example when we loop through the course or turn the result to a list:


foreach ( var c in courses)
    Console.WriteLine(c.Name);

OR
context.Courses
    .Where(c => c.Level == 1)
    .OrderBy(c => c.Name).ToList();

Comments

Post a Comment

Popular posts from this blog

Ensuring Data Integrity: The Role of Database Transactions

 1. What is database translation Database transactions are activities transferring, changing data from one consistent state to another consistent state for example in everyday life we make different kind of business transactions from buying products, changing or cancelling orders, buying tickets, etc. And all these activities involve the movement/transaction of data in the database. For example, consider a simple transaction of moving an amount of 5000 from one bank account to another. This transaction includes several steps: decrease the account balance by 5000, and then increase the other account balance by 50003. Each of these steps is a part of the transaction, and if any step fails, the entire transaction fails 2. Why it is crucial in reliable software systems? When it comes to business, whether it is personal or financial data, it is crucial to ensure the reliability and stability of data management. In our daily lives, we may frequently encounter errors related to database t...
Post a Comment
Read more

The Developer’s Guide to Clean Code: Tips and Techniques

What is clean code? Clean code is a term used to describe code that is easy to read, understand, and maintain. It is written in a way that makes it simple, concise, and expressive. Clean code follows a set of conventions, standards, and practices that make it easy to read and follow. Here are some signs indicating that the code is not clean: 1. Poor names The name is not clear to understand, meaningless, or misleading . It doesn't reveal the intention of what it want to achieve. Consider the following examples: SqlDataReader drl; int od; void Button1_Click(); Class Pages1 In the examples above, it’s challenging to get the purpose of drl, od, or what Button1_Click() does. To enhance clarity, we can rename these identifiers as follows: SqlDataReader dataReader/reader; int overdueDays; void CheckAvailability_Click(); Class ViewCustomerPage {} Ambiguous names int? incidentNameId for instance. incidentNameId lacks clarity because if it represents the ID of an incident, then the inclu...
Post a Comment
Read more