Save the multiselect options in database

Question

We created some "Brands" [values] in backend.

We have around 10 products in one category with category id = "40".

if we open any brand, we are displaying all those category products as multi-select option as below image.

but when we select options and click on "save", its not working.

why we want to save is , if we select particular Brand we want to display selected Products in dropdown in frontend as below image

Below code for displaying list of products in multi-select box.

$products = Mage::getModel('catalog/category')->load(40)
    ->getProductCollection()
    ->addAttributeToSelect('*');

$categorylist = array();
$categorylist[] = array(
    'value' => '', 'label' => Mage::helper('sales')->__('Category')
);
foreach ($products as $product) {
    $categorylist[] = array(
        'value' => $product->getEntityId(), 'label' => $product->getName()
    );
}
$fieldset->addField('category', 'multiselect',
    array(
        'label' => Mage::helper('sales')->__('Category'),
        'class' => 'required-entry',
        'required' => true,
        'values' => $categorylist,
        'name' => 'category',

    ));

Answer 1

$postData['category'] this will be your database table column name and $this->getRequest()->getPost('category') your form field name. implode function will be add , between the values.

$postData['category'] = implode(',',$this->getRequest()->getPost('category')); 

add in controller.php in saveAction

 $model = Mage::getModel('brand/brand');
 $data['products'] = implode(',',$this->getRequest()->getPost('category')); 
        $model->setData($data);