.NET Core uses the Entity Framework Core (EF Core) to connect to a database. EF Core is an object-relational mapper (ORM) that enables developers to interact with databases using C# objects rather than writing raw SQL.
To connect to a database in .NET Core, you need to perform the following steps:
- Install the appropriate database provider: EF Core supports a variety of database providers, such as SQL Server, MySQL, and PostgreSQL. You’ll need to install the appropriate package for the database you’re using, such as Microsoft.EntityFrameworkCore.SqlServer for SQL Server.
- Create a DbContext class: This class represents the database and is used to interact with it. It inherits from the Microsoft.EntityFrameworkCore.DbContext class, and you’ll need to configure it with the appropriate options for your database, such as the connection string.
- Register the DbContext class with the dependency injection container: This can be done in the ConfigureServices method of the Startup class by calling services.AddDbContext<DbContextClass>().
- Use the DbContext class to interact with the database: You can use the DbContext class to perform CRUD operations on the database, such as adding, updating, and deleting records.
- Dispose DbContext: Once you are done with the DbContext, make sure to dispose it to release the resources.
When the application starts, EF Core reads the connection string from the appsettings.json file, and creates the necessary database objects (tables, indexes, etc.) based on the entity classes defined in the DbContext class.
EF Core also provides support for database migration, which allows you to manage changes to the database schema over time. This allows you to evolve your database schema as your application changes without losing any data.
In addition to the steps mentioned above, here are a few more details on how .NET Core connects to a database using EF Core:
- The DbContext class is responsible for managing the database connection and interacting with the database. It contains a property called Database, which gives you access to the database and allows you to run raw SQL commands.
- EF Core also provides support for LINQ (Language Integrated Query), which allows you to query the database using C# code rather than writing raw SQL. This provides a more convenient and type-safe way of querying the database.
- To interact with the database, you can use the DbSet<T> class, which represents a table in the database. You can use methods like Add, Update, Remove, and Find to perform CRUD operations on the table.
- EF Core also supports lazy loading, which allows you to load related entities on demand instead of loading them all at once. This can improve performance by reducing the number of database queries.
- You can also use the EF Core’s built-in change tracking mechanism to track changes to entities and persist them to the database. This allows you to perform a single SaveChanges() operation to persist multiple changes to the database at once.
In summary, .NET Core uses the EF Core to connect to the database, which provides an easy and convenient way to interact with the database, it allows you to work with C# objects, use the LINQ for querying, perform the CRUD operations, track changes, and perform migrations.