我正试图从我的aws-rds-mysql示例中分块删除大量数据。我正在尝试修改这个链接中的代码，但是我遇到了一个无法修复的语法错误。
错误：

SQL Error (1064): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'main1: LOOP
    SELECT @z := operation_id FROM operations_test WHERE operation_id' at line 2

代码：

SET @apt = 'DTW'; 

SET @a = (SELECT MIN(operation_id) FROM operations_test);

BEGIN
    main1: LOOP
        SELECT @z := operation_id FROM operations_test WHERE operation_id >= @a ORDER BY operation_id LIMIT 1000,1;
        IF @z IS NULL THEN
          LEAVE main1;  -- last chunk
       END IF;
       DELETE operations_test, profiles_test FROM profiles_test LEFT JOIN operations_test ON operations_test.operation_id=profiles_test.operation_id WHERE operations_test.airport_id = @apt
            AND operations_test.operation_id >= @a
             AND operations_test.operation_id <  @z;
       DELETE operations_test FROM operations_test WHERE airport_id = @apt
            AND operation_id >= @a
             AND operation_id <  @z;
       SET @a = @z;
        SLEEP 1;  -- be a nice guy, especially in replication
    END LOOP main1;
END;

# Last chunk:

DELETE operations_test, profiles_test FROM profiles_test LEFT JOIN operations_test ON operations_test.operation_id=profiles_test.operation_id WHERE operations_test.airport_id = @apt
    AND id >= @a;
DELETE operations_test FROM operations_test WHERE airport_id = @apt
    AND id >= @a;