diff --git a/includes/wc-attribute-functions.php b/includes/wc-attribute-functions.php
index 250b46cc8e1..cb4df866ae6 100644
--- a/includes/wc-attribute-functions.php
+++ b/includes/wc-attribute-functions.php
@@ -2,23 +2,17 @@
 /**
  * WooCommerce Attribute Functions
  *
- * @author 		WooThemes
- * @category 	Core
- * @package 	WooCommerce/Functions
- * @version     2.1.0
+ * @package WooCommerce/Functions
+ * @version 2.1.0
  */
 
-if ( ! defined( 'ABSPATH' ) ) {
-	exit; // Exit if accessed directly
-}
+defined( 'ABSPATH' ) || exit;
 
 /**
  * Gets text attributes from a string.
  *
  * @since  2.4
- *
- * @param string $raw_attributes
- *
+ * @param string $raw_attributes Raw attributes.
  * @return array
  */
 function wc_get_text_attributes( $raw_attributes ) {
@@ -27,8 +21,9 @@ function wc_get_text_attributes( $raw_attributes ) {
 
 /**
  * See if an attribute is actually valid.
+ *
  * @since  3.0.0
- * @param  string $value
+ * @param  string $value Value.
  * @return bool
  */
 function wc_get_text_attributes_filter_callback( $value ) {
@@ -37,8 +32,9 @@ function wc_get_text_attributes_filter_callback( $value ) {
 
 /**
  * Implode an array of attributes using WC_DELIMITER.
+ *
  * @since  3.0.0
- * @param  array $attributes
+ * @param  array $attributes Attributes list.
  * @return string
  */
 function wc_implode_text_attributes( $attributes ) {
@@ -51,10 +47,12 @@ function wc_implode_text_attributes( $attributes ) {
  * @return array of objects
  */
 function wc_get_attribute_taxonomies() {
-	if ( false === ( $attribute_taxonomies = get_transient( 'wc_attribute_taxonomies' ) ) ) {
+	$attribute_taxonomies = get_transient( 'wc_attribute_taxonomies' );
+
+	if ( false === $attribute_taxonomies ) {
 		global $wpdb;
 
-		$attribute_taxonomies = $wpdb->get_results( "SELECT * FROM " . $wpdb->prefix . "woocommerce_attribute_taxonomies WHERE attribute_name != '' ORDER BY attribute_name ASC;" );
+		$attribute_taxonomies = $wpdb->get_results( "SELECT * FROM {$wpdb->prefix}woocommerce_attribute_taxonomies WHERE attribute_name != '' ORDER BY attribute_name ASC;" );
 
 		set_transient( 'wc_attribute_taxonomies', $attribute_taxonomies );
 	}
@@ -93,11 +91,15 @@ function wc_variation_attribute_name( $attribute_name ) {
 function wc_attribute_taxonomy_name_by_id( $attribute_id ) {
 	global $wpdb;
 
-	$attribute_name = $wpdb->get_var( $wpdb->prepare( "
+	$attribute_name = $wpdb->get_var(
+		$wpdb->prepare(
+			"
 		SELECT attribute_name
 		FROM {$wpdb->prefix}woocommerce_attribute_taxonomies
 		WHERE attribute_id = %d
-	", $attribute_id ) );
+	", $attribute_id
+		)
+	);
 
 	if ( $attribute_name && ! is_wp_error( $attribute_name ) ) {
 		return wc_attribute_taxonomy_name( $attribute_name );
@@ -123,8 +125,8 @@ function wc_attribute_taxonomy_id_by_name( $name ) {
 /**
  * Get a product attributes label.
  *
- * @param string $name
- * @param object $product object Optional
+ * @param string     $name    Attribute name.
+ * @param WC_Product $product Product data.
  * @return string
  */
 function wc_attribute_label( $name, $product = '' ) {
@@ -136,8 +138,14 @@ function wc_attribute_label( $name, $product = '' ) {
 		if ( $product->is_type( 'variation' ) ) {
 			$product = wc_get_product( $product->get_parent_id() );
 		}
+		$attributes = array();
+
+		if ( false !== $product ) {
+			$attributes = $product->get_attributes();
+		}
+
 		// Attempt to get label from product, as entered by the user.
-		if ( false !== $product && ( $attributes = $product->get_attributes() ) && isset( $attributes[ sanitize_title( $name ) ] ) ) {
+		if ( $attributes && isset( $attributes[ sanitize_title( $name ) ] ) ) {
 			$label = $attributes[ sanitize_title( $name ) ]->get_name();
 		} else {
 			$label = $name;
@@ -152,7 +160,7 @@ function wc_attribute_label( $name, $product = '' ) {
 /**
  * Get a product attributes orderby setting.
  *
- * @param mixed $name
+ * @param string $name Attribute name.
  * @return string
  */
 function wc_attribute_orderby( $name ) {
@@ -163,7 +171,7 @@ function wc_attribute_orderby( $name ) {
 	if ( isset( $wc_product_attributes[ 'pa_' . $name ] ) ) {
 		$orderby = $wc_product_attributes[ 'pa_' . $name ]->attribute_orderby;
 	} else {
-		$orderby = $wpdb->get_var( $wpdb->prepare( "SELECT attribute_orderby FROM " . $wpdb->prefix . "woocommerce_attribute_taxonomies WHERE attribute_name = %s;", $name ) );
+		$orderby = $wpdb->get_var( $wpdb->prepare( "SELECT attribute_orderby FROM {$wpdb->prefix}woocommerce_attribute_taxonomies WHERE attribute_name = %s;", $name ) );
 	}
 
 	return apply_filters( 'woocommerce_attribute_orderby', $orderby, $name );
@@ -175,7 +183,7 @@ function wc_attribute_orderby( $name ) {
  * @return array
  */
 function wc_get_attribute_taxonomy_names() {
-	$taxonomy_names = array();
+	$taxonomy_names       = array();
 	$attribute_taxonomies = wc_get_attribute_taxonomies();
 	if ( ! empty( $attribute_taxonomies ) ) {
 		foreach ( $attribute_taxonomies as $tax ) {
@@ -192,9 +200,11 @@ function wc_get_attribute_taxonomy_names() {
  * @return array
  */
 function wc_get_attribute_types() {
-	return (array) apply_filters( 'product_attributes_type_selector', array(
-		'select' => __( 'Select', 'woocommerce' ),
-	) );
+	return (array) apply_filters(
+		'product_attributes_type_selector', array(
+			'select' => __( 'Select', 'woocommerce' ),
+		)
+	);
 }
 
 /**
@@ -227,11 +237,11 @@ function wc_get_attribute_type_label( $type ) {
  * https://codex.wordpress.org/Function_Reference/register_taxonomy#Reserved_Terms.
  *
  * @since  2.4.0
- * @param  string $attribute_name
+ * @param  string $attribute_name Attribute name.
  * @return bool
  */
 function wc_check_if_attribute_name_is_reserved( $attribute_name ) {
-	// Forbidden attribute names
+	// Forbidden attribute names.
 	$reserved_terms = array(
 		'attachment',
 		'attachment_id',
@@ -309,14 +319,14 @@ function wc_check_if_attribute_name_is_reserved( $attribute_name ) {
 		'year',
 	);
 
-	return in_array( $attribute_name, $reserved_terms );
+	return in_array( $attribute_name, $reserved_terms, true );
 }
 
 /**
  * Callback for array filter to get visible only.
  *
  * @since  3.0.0
- * @param  WC_Product_Attribute $attribute
+ * @param  WC_Product_Attribute $attribute Attribute data.
  * @return bool
  */
 function wc_attributes_array_filter_visible( $attribute ) {
@@ -327,7 +337,7 @@ function wc_attributes_array_filter_visible( $attribute ) {
  * Callback for array filter to get variation attributes only.
  *
  * @since  3.0.0
- * @param  WC_Product_Attribute $attribute
+ * @param  WC_Product_Attribute $attribute Attribute data.
  * @return bool
  */
 function wc_attributes_array_filter_variation( $attribute ) {
@@ -338,8 +348,8 @@ function wc_attributes_array_filter_variation( $attribute ) {
  * Check if an attribute is included in the attributes area of a variation name.
  *
  * @since  3.0.2
- * @param  string $attribute Attribute value to check for
- * @param  string $name      Product name to check in
+ * @param  string $attribute Attribute value to check for.
+ * @param  string $name      Product name to check in.
  * @return bool
  */
 function wc_is_attribute_in_product_name( $attribute, $name ) {
@@ -352,7 +362,7 @@ function wc_is_attribute_in_product_name( $attribute, $name ) {
  * class PHP FALSE equivalents normally.
  *
  * @since 3.1.0
- * @param mixed $attribute  Attribute being considered for exclusion from parent array.
+ * @param mixed $attribute Attribute being considered for exclusion from parent array.
  * @return bool
  */
 function wc_array_filter_default_attributes( $attribute ) {
@@ -369,11 +379,15 @@ function wc_array_filter_default_attributes( $attribute ) {
 function wc_get_attribute( $id ) {
 	global $wpdb;
 
-	$data = $wpdb->get_row( $wpdb->prepare( "
+	$data = $wpdb->get_row(
+		$wpdb->prepare(
+			"
 		SELECT *
 		FROM {$wpdb->prefix}woocommerce_attribute_taxonomies
 		WHERE attribute_id = %d
-	 ", $id ) );
+	 ", $id
+		)
+	);
 
 	if ( is_wp_error( $data ) || is_null( $data ) ) {
 		return null;
@@ -431,10 +445,13 @@ function wc_create_attribute( $args ) {
 
 	// Validate slug.
 	if ( strlen( $slug ) >= 28 ) {
+		/* translators: %s: attribute slug */
 		return new WP_Error( 'invalid_product_attribute_slug_too_long', sprintf( __( 'Slug "%s" is too long (28 characters max). Shorten it, please.', 'woocommerce' ), $slug ), array( 'status' => 400 ) );
 	} elseif ( wc_check_if_attribute_name_is_reserved( $slug ) ) {
+		/* translators: %s: attribute slug */
 		return new WP_Error( 'invalid_product_attribute_slug_reserved_name', sprintf( __( 'Slug "%s" is not allowed because it is a reserved term. Change it, please.', 'woocommerce' ), $slug ), array( 'status' => 400 ) );
 	} elseif ( ( 0 === $id && taxonomy_exists( wc_attribute_taxonomy_name( $slug ) ) ) || ( isset( $args['old_slug'] ) && $args['old_slug'] !== $args['slug'] && taxonomy_exists( wc_attribute_taxonomy_name( $slug ) ) ) ) {
+		/* translators: %s: attribute slug */
 		return new WP_Error( 'invalid_product_attribute_slug_already_exists', sprintf( __( 'Slug "%s" is already in use. Change it, please.', 'woocommerce' ), $slug ), array( 'status' => 400 ) );
 	}
 
@@ -514,24 +531,27 @@ function wc_create_attribute( $args ) {
 			$table_name = get_option( 'db_version' ) < 34370 ? $wpdb->prefix . 'woocommerce_termmeta' : $wpdb->termmeta;
 			$wpdb->update(
 				$table_name,
-				array( 'meta_key' => 'order_pa_' . sanitize_title( $data['attribute_name'] ) ),
-				array( 'meta_key' => 'order_pa_' . sanitize_title( $args['old_slug'] ) )
+				array( 'meta_key' => 'order_pa_' . sanitize_title( $data['attribute_name'] ) ), // WPCS: slow query ok.
+				array( 'meta_key' => 'order_pa_' . sanitize_title( $args['old_slug'] ) ) // WPCS: slow query ok.
 			);
 
 			// Update product attributes which use this taxonomy.
 			$old_attribute_name_length = strlen( $args['old_slug'] ) + 3;
 			$attribute_name_length     = strlen( $data['attribute_name'] ) + 3;
 
-			$wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->postmeta} SET meta_value = REPLACE( meta_value, %s, %s ) WHERE meta_key = '_product_attributes'",
-				's:' . $old_attribute_name_length . ':"pa_' . $args['old_slug'] . '"',
-				's:' . $attribute_name_length . ':"pa_' . $data['attribute_name'] . '"'
-			) );
+			$wpdb->query(
+				$wpdb->prepare(
+					"UPDATE {$wpdb->postmeta} SET meta_value = REPLACE( meta_value, %s, %s ) WHERE meta_key = '_product_attributes'",
+					's:' . $old_attribute_name_length . ':"pa_' . $args['old_slug'] . '"',
+					's:' . $attribute_name_length . ':"pa_' . $data['attribute_name'] . '"'
+				)
+			);
 
 			// Update variations which use this taxonomy.
 			$wpdb->update(
 				$wpdb->postmeta,
-				array( 'meta_key' => 'attribute_pa_' . sanitize_title( $data['attribute_name'] ) ),
-				array( 'meta_key' => 'attribute_pa_' . sanitize_title( $args['old_slug'] ) )
+				array( 'meta_key' => 'attribute_pa_' . sanitize_title( $data['attribute_name'] ) ), // WPCS: slow query ok.
+				array( 'meta_key' => 'attribute_pa_' . sanitize_title( $args['old_slug'] ) ) // WPCS: slow query ok.
 			);
 		}
 	}
@@ -549,7 +569,7 @@ function wc_create_attribute( $args ) {
  * For available args see wc_create_attribute().
  *
  * @since  3.2.0
- * @param  int $id Attribute ID.
+ * @param  int   $id   Attribute ID.
  * @param  array $args Attribute arguments.
  * @return int|WP_Error
  */
@@ -564,12 +584,15 @@ function wc_update_attribute( $id, $args ) {
 		$args['name'] = $attribute->name;
 	}
 
-	$args['old_slug'] = $wpdb->get_var( $wpdb->prepare( "
+	$args['old_slug'] = $wpdb->get_var(
+		$wpdb->prepare(
+			"
 		SELECT attribute_name
 		FROM {$wpdb->prefix}woocommerce_attribute_taxonomies
 		WHERE attribute_id = %d
 	", $args['id']
-	) );
+		)
+	);
 
 	return wc_create_attribute( $args );
 }
@@ -584,11 +607,15 @@ function wc_update_attribute( $id, $args ) {
 function wc_delete_attribute( $id ) {
 	global $wpdb;
 
-	$name = $wpdb->get_var( $wpdb->prepare( "
+	$name = $wpdb->get_var(
+		$wpdb->prepare(
+			"
 		SELECT attribute_name
 		FROM {$wpdb->prefix}woocommerce_attribute_taxonomies
 		WHERE attribute_id = %d
-	", $id ) );
+	", $id
+		)
+	);
 
 	$taxonomy = wc_attribute_taxonomy_name( $name );
 
@@ -601,7 +628,7 @@ function wc_delete_attribute( $id ) {
 	 */
 	do_action( 'woocommerce_before_attribute_delete', $id, $name, $taxonomy );
 
-	if ( $name && $wpdb->query( "DELETE FROM {$wpdb->prefix}woocommerce_attribute_taxonomies WHERE attribute_id = $id" ) ) {
+	if ( $name && $wpdb->query( $wpdb->prepare( "DELETE FROM {$wpdb->prefix}woocommerce_attribute_taxonomies WHERE attribute_id = %d", $id ) ) ) {
 		if ( taxonomy_exists( $taxonomy ) ) {
 			$terms = get_terms( $taxonomy, 'orderby=name&hide_empty=0' );
 			foreach ( $terms as $term ) {