Search post_content for keywords across entire database. Ugly but fast.

contentsearch.php

<?php
add_action(
		'after_setup_theme',
		function() {
			global $wpdb;

			foreach ( [ 'twitter.com', 'facebook.com', 'instagram.com', 'youtube.com', 'soundcloud.com' ] as $s ) {
				echo "\n$s";

				$results = $wpdb->get_results( "SELECT * FROM `wp_3_posts` WHERE `post_content` LIKE '%$s%' ORDER BY `ID` DESC LIMIT 200;" );
				//$results = $wpdb->get_results( "SELECT * FROM wp_3_posts LIMIT 10" );

				foreach ( $results as $result ) {
					preg_match_all( "/.*$s.*/i", $result->post_content, $matches );

					foreach ( $matches as $match ) {
						echo "\n $result->post_date $result->ID \n";
						var_export( $match[0] );
					}
				}
			}

			die();
		}
);