This course will be retired on June 1, 2025.

Heads up! To view this whole video, sign in with your Courses account or enroll in your free 7-day trial. Sign In Enroll

Entity Framework Basics

Preview

Start a free Courses trial
to watch this video

Sign up for Treehouse

Filtering Queries

4:22 with James Churchill

Let's see how we can filter the results of a query using the `Where` LINQ operator.

Follow Along

To follow along commiting your changes to this course, you'll need to fork the dotnet-comic-book-gallery-model repo. Then you can clone, commit, and push your changes to your fork like this: 

git clone <your-fork>
cd dotnet-comic-book-gallery-model
git checkout tags/v4.2 -b filtering-queries

Case Sensitivity

Here are some additional resources for learning more about configuring SQL Server collations in order to control case-sensitivity.

Here's a resource that shows a way to selectively enabled case-sensitive search.

Additional Learning

Related Discussions

Have questions about this video? Start a discussion with the community and Treehouse staff.

Sign up

    Related Discussions

    Have questions about this video? Start a discussion with the community and Treehouse staff.

    Sign up

    Our list query is currently retrieving all of the comic books from the database. 0:00
    A typical requirement is to retrieve a list of entities that match 0:05
    a set of criteria. 0:08
    This is known as filtering. 0:10
    We can filter the results of a query by using the where link operator. 0:12
    .Where(cb => cb.IssueNumber == 1). 0:20
    This query will return all of the comic books that have an issue number of 1. 0:28
    Before we test our query, let's use a for 0:33
    each loop to write each comic book's display text property to the console. 0:36
    For each var comicBook in 0:42
    comicBooks console.WriteLine 0:47
    comicBook DisplayText. 0:54
    Let's also include the comic book series property. 0:59
    .include cb goes to cb.series. 1:04
    And lastly add an additional Console.WriteLine method call in order to 1:11
    add a blank line between the list of comic books and the comic book count. 1:16
    Console.WriteLine. 1:24
    Our query returned a total of three comic books. 1:30
    And the generated query now contains a WHERE clause. 1:34
    We can add multiple calls to the where 1:46
    method in order to filter by more than 1:51
    one expression .where cb goes to 1:56
    cb.Series.Title = The Amazing Spider-Man. 2:01
    This query will return all comic books whose issue number is one and 2:07
    whose series title is The Amazing Spider-Man. 2:12
    An alternative way to write this query, 2:15
    is to combine the filtering expressions into a single conditional statement. 2:17
    If we wanted to get all the comic books whose issue number is one or who's 2:24
    series title is The Amazing Spider-Man we can change the conditional and 2:29
    operator to a conditional or. 2:33
    Our query now returns a total of five comic books. 2:40
    And the query's WHERE clause now contains two conditions separated by the OR 2:47
    keyword. 2:52
    Using the equality operator, 2:57
    we'll require that the comic book series title match a provided string. 2:59
    If we want all of the comic books whose series titles contained the string man, 3:03
    we can switch to using the string contains method. 3:07
    Where cb goes to cb.series.Title.Contains. 3:12
    Man. 3:24
    Now, our query returns a total of 6 comic books. 3:29
    And the queries where clause is using the like operator with wildcards surrounding 3:35
    our search text, which is the SQL way of performing a contained search. 3:40
    In this query, our man's search text with a lowercase m 3:45
    matched column values containing man with an uppercase M. 3:49
    Generally speaking when using EF the casing of the string 3:54
    doesn't matter when filtering data. 3:57
    Though that behavior depends on how your database server is configured. 4:00
    By default SQL Server is configured to be case insensitive. 4:04
    Though it's possible to change this configuration. 4:08
    For more information on case sensitivity and EF and 4:12
    SQL Server, see the teacher's notes. 4:14
    After a short code challenge we'll see how we can order the results of our query. 4:17

    You need to sign up for Treehouse in order to download course files.

    Sign up

      You need to sign up for Treehouse in order to set up Workspace

      Sign up