显示接收方和发送方信息的 KSQL 查询答案

【问题标题】：KSQL query to display receiver and sender info显示接收方和发送方信息的 KSQL 查询
【发布时间】：2020-05-14 00:36:57
【问题描述】：

我有一个名为users 的表，如下所示：

 +----+----------------+
 | id | name           | 
 +----+----------------+
 |  1 | Blake          | 
 |  2 | Jenn           | 
 +----+----------------+

我有一个名为transactions 的流，看起来像这样：

 +----+----------------+----------------+
 | id | sender         | receiver       | 
 +----+----------------+----------------+
 |  1 | 1              | 2              |
 |  2 | 2              | 1              |
 +----+----------------+----------------+

所以基本上我想要的结果是这样的：

 +----+----------------+----------------+----------------+----------------+
 | id | sender         | sender_name    | receiver       |receiver_name  |
 +----+----------------+----------------+----------------+----------------+
 |  1 | 1              | Blake          | 2              | Jenn           |
 |  2 | 2              | Jenn           | 1              | Blake          |
 +----+----------------+----------------+----------------+----------------+

我只设法加入由发送者或接收者分区的流和表，因此我只能获取发送者信息或接收者信息。

【问题讨论】：

标签： apache-kafka ksqldb

【解决方案1】：

您可以对users 表使用两次JOIN 以获得预期结果：

SELECT TR.id, TR.sender, SE.name AS sender_name, TR.receiver, RE.name AS receiver_name
FROM transactions TR
JOIN users SE ON SE.id = TR.sender
JOIN users RE ON RE.id = TR.receiver

【讨论】：

【解决方案2】：

关键是创建一个流来显示它，我已经尝试过您实际描述的方法，但我认为它在 ksql 上不起作用，因为它需要一个 ';'在第一次内部连接之后。

Statement: create stream  userstransactionsjoinedfinal as select t.txid,t.sender,    
up1.firstname as senderfirstname,up1.lastname as senderlastname,up1.phonenumber as 
senderphonenumber,up1.email as senderemail,t.receiver,up2.firstname as 
receiverfirstname,up2.lastname as receiverlastname,up2.phonenumber as 
receiverphonenumber,up2.email as receiveremail,  t.SENDERWALLETID,  
t.RECEIVERWALLETID,t.status,t.type,t.amount,t.totalfee from transactionsrekeyed 
inner join usersnow up1 on up1.id=t.sender inner join usersnow up2 on up2.id = 
t.receiver;
Caused by: line 1:483: mismatched input 'inner' expecting ';'
Caused by: org.antlr.v4.runtime.InputMismatchException

【讨论】：