Magento2 – Add Data from Custom Module to Core Database

Please add the following code in the config.xml file.

 <global>
    <rewrite>
        <customcontactus>
            <from><![CDATA[#^/contacts/index/#]]></from>
            <to>/contactform/index/</to>
        </customcontactus>
    </rewrite>
</global>

Rewrite the postAction() controller file and add the following code.

$model = Mage::getModel("contactform/contactformsave");
            $model->setData(array('created_at'=>NOW(),'name'=>$post['name'],
                'email'=>$post['email'],'telephone'=>$post['telephone'],
                'comment'=>$post['comment']));
            $model->save();

            Mage::getSingleton('customer/session')->addSuccess(Mage::helper('contacts')->
                    __('Your inquiry was submitted and will be responded to as soon as possible. Thank you for contacting us.'));
            $this->_redirect('*/*/');

Please refer my tutorial for full code and file structure.

http://www.pearlbells.co.uk/save-contact-form-data-magento-database/

1) I Assume you have created Model and Collection file associated with that tables.

2) In a Block PHP file constructor add one argument (Dependency Injection) like below and store it in a class member variable.

 public function __construct(
    Context $context,
    \Namespace\Modulename\Model\ModelNameFactory $modelNameFactory,

    array $data = array()
) {
    $this->_modelFactory = $modelFactory;
    parent::__construct($context, $data);
}

3) Prepare a public method in your block to access collection like below.

public function getCollection(){

    return $this->_modelFactory->create()->getCollection();

}

4) Loop through each of the collection result.

Hope, this will help you.