How to Execute a Complex MySQL Query in Rails Using ActiveRecord

Learn how to run complex MySQL queries in a Ruby on Rails application utilizing the capabilities of ActiveRecord. This guide covers essentials for executing raw SQL and integrating it seamlessly within Rails.
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How to Execute a Complex MySQL Query in Rails Using ActiveRecord

Using complex MySQL queries within a Ruby on Rails application can sometimes seem daunting, especially when you're leveraging ActiveRecord. However, Rails provides robust mechanisms to execute raw SQL queries, making it straightforward and efficient.

Why Use Raw SQL in Rails?

ActiveRecord, the default ORM for Rails, simplifies interactions with the database using a high-level API. However, scenarios may arise where:

Performance optimization: Certain operations are more efficiently executed as raw SQL.

Complex queries: Some intricate queries are easier to write in SQL directly.

Using database-specific features: Need to leverage database-specific optimizations or features not supported natively by ActiveRecord.

Executing Raw SQL with ActiveRecord

ActiveRecord makes it convenient to execute raw SQL queries. Here are a few methods to do so:

Using find_by_sql

The find_by_sql method allows execution of a SQL statement and returns an array of model instances.

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Using pluck and select

When you need specific columns or values, pluck and select methods can simplify the job.

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Handling SQL Injection

When executing raw SQL queries, it's critical to be aware of SQL injection vulnerabilities. Always sanitize inputs:

Use placeholders and bindings: ["SELECT * FROM users WHERE name = ?", name]

Utilize ActiveRecord’s methods wherever possible.

Conclusion