How to write Sub Queries in Codeigniter Active Record ?

Codeigniter didn’t provided any option to use sub queries with active record class. So today i would like to provide simple and possible comprehensive techniques on “creating Sub Queries with Codeigniter Active Record”.

Creating sub query in Codeigniter is as easy as creating the regular Active Record queries. The technique here is first we need to generate a query and the generated query we need to inject it into the main query as sub Query.

So first we need to generate a sub query and store that generated query in a variable as a string. After generating sub query we will generate main query by suing previously genreated query as sub query.

For Example – I am going to generate blow query with active record methods

1	SELECT * FROM employees WHERE id IN(SELECT id FROM employees_backup);

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// Sub Query $this->db->select('id')->from('employees_backup'); $subQuery =  $this->db->get_compiled_select(); // Main Query $this->db->select('*')          ->from('employees')          ->where("id IN ($subQuery)", NULL, FALSE)          ->get()          ->result();

The NULL,FALSE in the where() method tells CodeIgniter not to escape the query.

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