apache-kafka - 我可以在 KSQL 中编写子查询吗？

Question

我是新来的 ksql并且一直在使用mysql最长的时间。
我想知道无论如何在 KSQL 中有子查询?

这个查询没有任何问题:

SELECT a.executedate, count(a.pno), sum(a.amount) FROM
tb3_withdraw_record_summary a WHERE a.status='3' GROUP BY
a.executedate;

而此查询返回错误消息:

SELECT a.executedate, count(a.pno), sum(a.amount), (SELECT COUNT(b.pno)
FROM tb3_withdraw_record_summary b WHERE b.status='5' AND
b.executedate = a.executedate) FROM tb3_withdraw_record_summary a
WHERE a.status='3' GROUP BY a.executedate

'Failed to prepare statement: 'B' is not a valid stream/table name or alias. Caused by: 'B' is not a valid stream/table name or alias.'

无论如何让我完成这项工作？谢谢!

Answer 1

Ksql 目前不支持嵌套查询功能，但您可以通过以下方式进行 -

1) CREATE STREAM B AS SELECT COUNT(b.pno)
FROM tb3_withdraw_record_summary b WHERE b.status='5';
2) SELECT a.executedate, count(a.pno), sum(a.amount) FROM tb3_withdraw_record_summary a JOIN B within 5 hours ON b.executedate = a.executedate WHERE a.status='3' GROUP BY a.executedate

请记住，连接与关系数据库世界的含义非常不同，这里的数据通过多个存储桶中的键进行分区，并且在概念上是“共置”连接。更多详情 time-window这里。

希望它会有所帮助。