What is the difference between active record and query builder in CodeIgniter?

In CodeIgniter, both Active Record and Query Builder are database querying methods that simplify interacting with databases, but they have distinct approaches and functionalities:

Active Record:

1. Object-Oriented Approach: Active Record in CodeIgniter follows an object-oriented paradigm, allowing you to interact with the database using a more intuitive and object-like syntax. You work with database records as objects, making it easier to understand and maintain your code.

2. Table-Centric: Active Record is more table-centric, meaning that it focuses on individual database tables. You typically create an Active Record instance associated with a specific database table, and then you can perform CRUD (Create, Read, Update, Delete) operations on records within that table.

3. Method Chaining: Active Record supports method chaining, where you can chain multiple database operations together in a fluid and readable manner. This makes it easy to build complex queries step by step.

4. Built-in Functions: CodeIgniter’s Active Record library provides various built-in functions for common database operations, such as `insert()`, `get()`, `update()`, and `delete()`. These functions simplify the process of constructing queries.

Query Builder:

1. Fluent Interface: Query Builder, on the other hand, offers a fluent interface for constructing database queries. It allows you to build SQL queries programmatically through a chain of method calls, making it flexible and dynamic.

2. Table-Agnostic: Unlike Active Record, Query Builder is more table-agnostic, meaning it doesn’t require an instance associated with a specific table. You can construct queries that involve multiple tables or custom SQL expressions easily.

3. Fine-Grained Control: Query Builder provides more fine-grained control over query construction. You can create complex queries with specific joins, conditions, and expressions, making it suitable for scenarios where precise control over SQL statements is required.

4. Versatility: Query Builder is versatile and allows you to build a wide range of queries, including JOINs, subqueries, and complex WHERE conditions, without relying on CodeIgniter’s built-in functions.

The main difference between Active Record and Query Builder in CodeIgniter lies in their approach and level of control. Active Record offers a more object-oriented and simplified way to interact with individual database tables, while Query Builder provides a flexible, table-agnostic, and fine-grained approach for constructing complex SQL queries, making it suitable for a broader range of database interactions. The choice between the two depends on the specific requirements and complexity of your database operations.