--- /dev/null
+<?php
+
+namespace Drupal\comment\Plugin\views\sort;
+
+use Drupal\views\Plugin\views\sort\SortPluginBase;
+
+/**
+ * Sort handler to sort by last comment name which might be in 2 different
+ * fields.
+ *
+ * @ingroup views_sort_handlers
+ *
+ * @ViewsSort("comment_ces_last_comment_name")
+ */
+class StatisticsLastCommentName extends SortPluginBase {
+
+ public function query() {
+ $this->ensureMyTable();
+ $definition = [
+ 'table' => 'users_field_data',
+ 'field' => 'uid',
+ 'left_table' => 'comment_entity_statistics',
+ 'left_field' => 'last_comment_uid',
+ ];
+ $join = \Drupal::service('plugin.manager.views.join')->createInstance('standard', $definition);
+
+ // @todo this might be safer if we had an ensure_relationship rather than guessing
+ // the table alias. Though if we did that we'd be guessing the relationship name
+ // so that doesn't matter that much.
+ $this->user_table = $this->query->ensureTable('ces_users', $this->relationship, $join);
+ $this->user_field = $this->query->addField($this->user_table, 'name');
+
+ // Add the field.
+ $this->query->addOrderBy(NULL, "LOWER(COALESCE($this->user_table.name, $this->tableAlias.$this->field))", $this->options['order'], $this->tableAlias . '_' . $this->field);
+ }
+
+}