How can I execute UNION queries using CodeIgniter's ActiveRecord pattern?

Union Queries with CodeIgniter's ActiveRecord Pattern

The ActiveRecord pattern, widely used in CodeIgniter, offers a convenient way to perform database operations. However, it does not natively support UNION queries. There is a workaround, though, that involves writing your own query and utilizing the ActiveRecord's query method.

Query Construction

To execute a UNION query, start by composing your query string as follows:

SELECT column_name(s) FROM table_name1
UNION
SELECT column_name(s) FROM table_name2

CodeIgniter Implementation

Once your query is ready, use CodeIgniter's DB class to execute it:

$this->db->query('SELECT column_name(s) FROM table_name1 UNION SELECT column_name(s) FROM table_name2');

This query will perform a UNION operation, combining the results from table_name1 and table_name2 into a single set of records.

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