Cara menggabungkan 2 table database

Selamat siang Saya mau minta tolong, saya punya masalah untuk menggabungkan 2 table database menjadi 1 output. script seperti ini:

function alf_product_item_meta( $ids ){
	global $wpdb;
	$meta_data = array();
	if( !empty( $ids ) ){
		$results = $wpdb->get_results(
		"SELECT COUNT(*) AS merchants, MIN(price) as minPrice, MIN(price_streak) as strPrice, MIN(price_disc) as dscPrice, product_link as linkProduct, post_id FROM {$wpdb->prefix}product_listing WHERE post_id GROUP BY post_id"
);
		if( !empty( $results ) ){
			foreach( $results as $result ){
				    $meta_data[$result->post_id] = array(
					'merchants' => $result->merchants,
					'minPrice' => $result->minPrice,
					'strPrice' => $result->strPrice,
					'dscPrice' => $result->dscPrice,
					'linkProduct' => $result->linkProduct
				);
			}
		}
	}

	return $meta_data;
}

dan database seperti ini:

    CREATE TABLE {$wpdb->prefix}product_listing (
feed_id mediumint(9) NOT NULL AUTO_INCREMENT,
	  post_id mediumint(9) NOT NULL,
	  merchant_id mediumint(9) NOT NULL,
	  price double NOT NULL,
	  price_streak double NOT NULL,
	  price_disc double NOT NULL,
	  product_link text DEFAULT '' NOT NULL,

CREATE TABLE {$wpdb->prefix}merchants (
          merchant_id mediumint(9) NOT NULL AUTO_INCREMENT,
	  merchant_slug varchar(255) NOT NULL,
	  merchant_logo varchar(10) NOT NULL,

output:

<?php
	$args = array(
		'post_type' => 'product',
		'post_status' => 'publish',
		'orderby' => 'meta_value_num',
		'order' => 'DESC' );

			$products = new WP_Query($args);
	        $product_ids = wp_list_pluck( $products->posts, 'ID' );
	        $product_metas = alf_product_item_meta( $product_ids );
			$min_price = !empty( $product_metas[get_the_ID()] ) ? $product_metas[get_the_ID()]['minPrice'] : 0;
			$link_product = !empty( $product_metas[get_the_ID()] ) ? $product_metas[get_the_ID()]['linkProduct'] : 0;
			$merchants = !empty( $product_metas[get_the_ID()] ) ? $product_metas[get_the_ID()]['merchants'] : 0;


            if ( $products->have_posts() ): $products->the_post();
 echo _e('HARGA TERENDAH','alf');?>   <span class="price-single">
 <?php echo alf_format_currency_number( $min_price ) ; ?>
  Di <?php
echo wp_get_attachment_image( $merchants ) ?><span class="link-product"><a href="<?php echo esc_url( $link_product ) ?>" target="_blank">Lihat Toko</a></span></span></p><?php
	wp_reset_query();
wp_reset_postdata()	;
endif;
?>

PERTANYAANNYA: Gimana cara menampilkan output berupa gambar dari row "merchant_logo"

Mohon pencerahannya. Tq