SQL requests Ruby on Rails

Learn how to write SQL queries in Ruby on Rails with an example, from building a basic query to advanced search techniques.

Using SQL with Ruby on Rails

Ruby on Rails is a popular web development framework, and it has support for working with SQL databases. You can quickly set up your models to work with SQL databases, and then use SQL commands to manipulate and retrieve data.

One of the most common uses for SQL with Rails is to query a database for data. You can use the ActiveRecord query interface to write SQL queries in Ruby. An example of a query to find the user with an id of 15 would look like this:

User.find(15)

In this example, the User class is a model that is linked to a SQL table. The find method is used to query the database for a record with an id of 15. The result of this query is a single record from the database, which is represented as an instance of the User class.

You can also use ActiveRecord to create SQL queries that contain more complex logic. For example, if you wanted to find all the users who have an email address that ends in 'example.com', you could write the following query:

User.where('email LIKE ?', '%example.com')

The where method is used to specify conditions in the query, and the 'LIKE ?' syntax is used to create a pattern match for the email address. In this example, the query will return all the users who have an email address that ends in 'example.com'.

You can also use SQL commands directly in your Rails code. This is useful if you need to run a custom query that cannot be expressed using the ActiveRecord query interface. To do this, you can use the ActiveRecord connection object to execute SQL commands directly. For example, if you wanted to find all the users whose email addresses contain 'example.com', you could write the following query:

ActiveRecord::Base.connection.execute('SELECT * FROM users WHERE email LIKE "%example.com%"')

In this example, the ActiveRecord connection is used to execute a SQL query directly. The results of the query are returned as an array of hashes, each hash representing a single record from the database.

Working with SQL in Ruby on Rails is relatively straightforward. With the ActiveRecord query interface, you can easily write queries to retrieve data from the database. You can also use the ActiveRecord connection object to execute SQL commands directly, which can be useful for more complex queries or custom logic.