How Can I Execute UNION Queries Using CodeIgniter's Active Record?

Executing UNION Queries in CodeIgniter's Active Record

CodeIgniter's Active Record pattern provides a powerful way to interact with databases. However, it lacks built-in support for UNION queries. To overcome this limitation, you can directly execute SQL queries using the query method.

Query Syntax

To perform a UNION query using CodeIgniter's Active Record, use the following syntax:

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

In this query, the column_name(s) represents the columns you want to retrieve, and table_name1 and table_name2 represent the tables to combine.

Example

Consider the following example:

$sql = "SELECT username FROM users
UNION
SELECT username FROM admins";

$query = $this->db->query($sql);

This query will retrieve the username column from both the users and admins tables, combining the results into a single list.

Note:

Remember that UNION queries require the columns in both tables to be of the same data type and order. Otherwise, an error will occur.

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