How to create attributes programmatically in magento?

Please add function in sql script

private function createAttribute($code, $label, $attribute_type, $product_type)
{       
    $_attribute_data = array(
        'attribute_code' => 'old_site_attribute_'.(($product_type) ? $product_type : 'joint').'_'.$code,
        'is_global' => '1',
        'frontend_input' => $attribute_type, //'boolean',
        'default_value_text' => '',
        'default_value_yesno' => '0',
        'default_value_date' => '',
        'default_value_textarea' => '',
        'is_unique' => '0',
        'is_required' => '0',
        'apply_to' => array($product_type), //array('grouped')
        'is_configurable' => '0',
        'is_searchable' => '0',
        'is_visible_in_advanced_search' => '0',
        'is_comparable' => '0',
        'is_used_for_price_rules' => '0',
        'is_wysiwyg_enabled' => '0',
        'is_html_allowed_on_front' => '1',
        'is_visible_on_front' => '0',
        'used_in_product_listing' => '0',
        'used_for_sort_by' => '0',
        'frontend_label' => array('Old Site Attribute '.(($product_type) ? $product_type : 'joint').' '.$label)
    );


    $model = Mage::getModel('catalog/resource_eav_attribute');

    if (!isset($_attribute_data['is_configurable'])) {
        $_attribute_data['is_configurable'] = 0;
    }
    if (!isset($_attribute_data['is_filterable'])) {
        $_attribute_data['is_filterable'] = 0;
    }
    if (!isset($_attribute_data['is_filterable_in_search'])) {
        $_attribute_data['is_filterable_in_search'] = 0;
    }

    if (is_null($model->getIsUserDefined()) || $model->getIsUserDefined() != 0) {
        $_attribute_data['backend_type'] = $model->getBackendTypeByInput($_attribute_data['frontend_input']);
    }

    $defaultValueField = $model->getDefaultValueByInput($_attribute_data['frontend_input']);
    if ($defaultValueField) {
        $_attribute_data['default_value'] = $this->getRequest()->getParam($defaultValueField);
    }


    $model->addData($_attribute_data);

    $model->setEntityTypeId(Mage::getModel('eav/entity')->setType('catalog_product')->getTypeId());
    $model->setIsUserDefined(1);


    try {
        $model->save();
    } catch (Exception $e) { echo '<p>Sorry, error occured while trying to save the attribute. Error: '.$e->getMessage().'</p>'; }
}

The import I was running had to deal with grouped and simple products (that go on that grouped products). Besides special attributes that only grouped products had, and some special attributes that only simple products have, system also had some “joint” attributes that both of the product types had. Examples below show how I called the above method to generate such specific or “joint” attributes.

//My "grouped product only" attribute
$this->createAttribute(strtolower("ShirtType"), "ShirtType", "select", "grouped");


//My "simple product only" attribute
$this->createAttribute(strtolower("Swatch"), "Swatch", "text", "simple");


//My "joint" attribute, the one that I had both on simple and on grouped products
$this->createAttribute(strtolower("InventoryMsg"), "InventoryMsg", "text", "");
$this->createAttribute(strtolower("Complete"), "Complete", "boolean", "");