Querying Data

Entity Framework Core uses Language-Integrated Query (LINQ) to query data from the database. LINQ allows you to use C# (or your .NET language of choice) to write strongly typed queries. It uses your derived context and entity classes to reference database objects. EF Core passes a representation of the LINQ query to the database provider. Database providers in turn translate it to database-specific query language (for example, SQL for a relational database). Queries are always executed against the database even if the entities returned in the result already exist in the context.

The following snippets show a few examples of how to achieve common tasks with Entity Framework Core.

Loading all data

using (var context = new BloggingContext())
{
    var blogs = context.Blogs.ToList();
}

Loading a single entity

using (var context = new BloggingContext())
{
    var blog = context.Blogs
        .Single(b => b.BlogId == 1);
}

Filtering

using (var context = new BloggingContext())
{
    var blogs = context.Blogs
        .Where(b => b.Url.Contains("dotnet"))
        .ToList();
}

Further readings

• Learn more about LINQ query expressions
• For more detailed information on how a query is processed in EF Core, see How queries Work.