I wuold like to define a trigger to block the deletion of the row with ID 2 of the configuration table, you might guess why, I am trying something like that:

CREATE TRIGGER do_not_delete_configuration_1 BEFORE DELETE ON configuration
  FOR EACH ROW BEGIN
    IF (OLD.configurationid != 1) THEN
      DELETE FROM configuration WHERE configuration.configuration=OLD.configurationid;
    END IF;
  END;
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without a positive result.