SET @neo_has_apns_environment := (
  SELECT COUNT(*)
  FROM INFORMATION_SCHEMA.COLUMNS
  WHERE TABLE_SCHEMA = DATABASE()
    AND TABLE_NAME = 'device_tokens'
    AND COLUMN_NAME = 'apns_environment'
);

SET @neo_apns_environment_sql := IF(
  @neo_has_apns_environment = 0,
  'ALTER TABLE device_tokens ADD COLUMN apns_environment VARCHAR(20) NOT NULL DEFAULT ''production'' AFTER platform',
  'SELECT 1'
);

PREPARE neo_apns_environment_stmt FROM @neo_apns_environment_sql;
EXECUTE neo_apns_environment_stmt;
DEALLOCATE PREPARE neo_apns_environment_stmt;