Ignited Datatables search stop whorking when using SUM or AVG functions inside query

amantilak

Ignited Datatables search stop whorking when using SUM or AVG functions inside query

My Query
$this->load->library('datatables');
$this->datatables
->select('products.id as product_id,products.name as product_name,products.quantity as product_quantity, categories.name as category_name,AVG(purchase_items.unit_price) as avg_cost ,((products.quantity*AVG(purchase_items.unit_price))) as total_amount')
->from('products')
->join('categories', 'products.category_id=categories.id', 'left')
->join('purchase_items', 'products.id=purchase_items.product_id', 'left')
->where('products.quantity > 0', NULL)
->group_by('products.id');