Update query increment field plus 1 codeigniter

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Issue:

I got a problem when trying to increment by 1 on given field in my db. I tried with and without active records.

My functions look like this (in my model)

function _set_reads($id){
$this->db->set('reads', 'reads+1', FALSE)
$this->db->where('id', $id);
$this->db->update('article');
}

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and

function _set_reads($id){
$sql = 'update article set reads=reads+1 where id=?';
$this->db->query($sql, array($id));
}

I get the same error in both cases and it's the following error message:

Error Number: 1064

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'reads+1 WHERE `id` = '15'' at line 1

UPDATE 
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`article` SET `reads` = reads+1 WHERE `id` = '15'

Sol 1:

 Need small correction

$this->db->where('id', $id);
$this->db->set('set_row', '`set_row`+ 1', FALSE);

Thank You

Sol 2:

This was very helpful to @syyu

$this->db->where('id', $id);
$this->db->set('set_row', '`set_row`- 1', FALSE); // to decrement

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Sol 3:

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$this->db->where('image_id', $other_imageid);

$this->db->set('impressions', '`impressions`+1', FALSE );

$this->db->update('user_images');

Sol 4:

Sol 5: