Question

I have a set of IDs passed in a particular order which needs to be retained.
I am querying from several left joins the data related to each ID.
The IDs are returned from a search so the order must be kept to make the results valid (otherwise it makes searching rather pointless).

My code looks something like;

$this->db->where_in('id', $array_of_ordered_ids);

For example –

$this->db->where_in('id', array(4,5,2,6));

Will return the results in order 2,4,5,6.

I’d like for it to retain the order and return the results 4,5,2,6.

Thank you,

Answer 1

To order the result by the order in your array, you can do the following:

$array_of_ordered_ids = array(4,5,2,6);

As you already know the order of the numbers, you can use the Mysql FIELD()^Docs function:

ORDER BY FIELD(id, 4, 5, 2, 6);

To create such a string, you can use implode^Docs:

$order = sprintf('FIELD(id, %s)', implode(', ', $array_of_ordered_ids));

Give it a try:

$array_of_ordered_ids = array(4,5,2,6);
$this->db->where_in('id', $array_of_ordered_ids);
$order = sprintf('FIELD(id, %s)', implode(', ', $array_of_ordered_ids));
$this->db->order_by($order);