Update the SQL schema and template

The template had problems with string quoting (PHP
only allows interpolation in double-quoted strings!).

The SQL schema changes the primary key,
so we're switching to a different table to avoid
having to dedupe existing data.

ai-global-activity.php

@@ -13,7 +13,7 @@
 global $ai_activity_db_version;
 $ai_activity_db_version = '1.0';
 
-define('AI_ACTIVITY_TABLE_NAME', 'ai_activity');
+define('AI_ACTIVITY_TABLE_NAME', 'ai_global_activity');
 
 /* Database schema initialization */
 function ai_activity_install() {
@@ -24,7 +24,6 @@ function ai_activity_install() {
   $charset_collate = $wpdb->get_charset_collate();
 
   $sql = "CREATE TABLE $table_name (
-  id mediumint(9) NOT NULL AUTO_INCREMENT,
     blog_id integer(11) NOT NULL,
     post_id integer(11) NOT NULL,
     title text,
@@ -32,7 +31,7 @@ function ai_activity_install() {
     content text,
     url text,
     published_at datetime DEFAULT current_timestamp(),
-    PRIMARY KEY  (id),
+    PRIMARY KEY  (blog_id, post_id),
     KEY published_at (published_at)
   ) $charset_collate;";
 
@@ -77,7 +76,10 @@ function ai_activity_publish_post($post_id) {
   $post_content = get_the_content('more...', true, $post);
   $post_author = apply_filters('the_author', $post->post_author);
 
-  $wpdb->insert(
+  // If another entry for the same blog_id/post_id exists,
+  // we want to overwrite it (likely someone editing an already
+  // published post).
+  $wpdb->replace(
 		AI_ACTIVITY_TABLE_NAME,
 		array(
                       'title' => $post_title,
@@ -116,7 +118,7 @@ function ai_activity_get_latest_posts($offset, $limit) {
   $results = $wpdb->get_results($wpdb->prepare(
                                                "
                                                SELECT blog_id, post_id, title, author, content, url, published_at
-                                               FROM $table_name
+                                               FROM {$table_name}
                                                ORDER BY published_at DESC
                                                LIMIT %d OFFSET %d
                                                ",
@@ -150,39 +152,39 @@ function ai_activity_display_recent_posts($tmp_number, $tmp_title_characters, $t
         if ($tmp_title_link == 'no') {
           $html .= $title_short;
         } else {
-          $html .= '<a href="{$post_url}" >${title_short}</a>';
+          $html .= "<a href=\"{$post_url}\" >{$title_short}</a>";
         }
 
         if ($show_blog) {
           $blog_details = get_blog_details($blog_id);
           $site_url = get_site_url($blog_id);
           $class = 'blog-info';
-          $post_blog = '<span class="{$class}">
-              <a href="{$site_url}">{$blog_details->blogname}</a>
-              </span>';
+          $post_blog = "<span class=\"{$class}\">
+              <a href=\"{$site_url}\">{$blog_details->blogname}</a>
+              </span>";
 
           $post_blog = apply_filters('recent_network_posts_post_blog',
                                      $post_blog,
                                      $blog_id);
 
-          $html .= ' (<a href="{$site_url}">{$blog_details->blogname}</a>)';
+          $html .= " (<a href=\"{$site_url}\">{$blog_details->blogname}</a>)";
         }
-          $html .= '</div>';
+        $html .= "</div>";
       }
 
-      $html .= '<div class="post-content">{$post->content}</div>';
-      $html .= '</div>';
+      $html .= "<div class=\"post-content\">{$post->content}</div>";
+      $html .= "</div>";
     }
   }
 
   $html .= '<div class="global-activity-pagination">';
   $prev_link = ai_activity_get_previous_page_link();
   if ($prev_link) {
-    $html .= '<div class="nav-previous align-left"><a href="{$prev_link}">Newer</a></div>';
+    $html .= "<div class=\"nav-previous align-left\"><a href=\"{$prev_link}\">Newer</a></div>";
   }
   $next_link = ai_activity_get_next_page_link();
   if ($next_link) {
-    $html .= '<div class="nav-next align-right"><a href="{$next_link}">Older</a></div>';
+    $html .= "<div class=\"nav-next align-right\"><a href=\"{$next_link}\">Older</a></div>";
   }
   $html .= '</div>';