crud queries in Drupal 8

$result = $connection->insert('mytable')
  ->fields([
    'title' => 'Example',
    'uid' => 1,
    'created' => \Drupal::time()->getRequestTime(),
  ])
  ->execute();

insert, update, delete, upsert

https://www.drupal.org/docs/drupal-apis/database-api/insert-queries
https://www.drupal.org/docs/drupal-apis/database-api/update-queries
https://www.drupal.org/docs/8/api/database-api/delete-queries
https://www.drupal.org/docs/drupal-apis/database-api/upsert-queries