cassandra - 如何执行表查询？ [英] cassandra - how to perform table query?

问题描述

我尝试使用两个表执行查询：

I am trying to perform a query using 2 tables:

CREATE TABLE users(
  id_ UUID PRIMARY KEY,
  username text,
  email text,
  );

CREATE TABLE users_by_email(
  id UUID,
  email text PRIMARY KEY
)

在这种情况下，如何通过电子邮件执行查询？

In this cas, how to perform a query by email?

推荐答案

我假设您还希望在查询中返回 username 。您不能在Cassandra中JOIN表。为此，您必须将该列添加到您的 users_by_email 表中：

I am assuming that you also want username returned in the query. You cannot JOIN tables in Cassandra. So to do that, you will have to add that column to your users_by_email table:

CREATE TABLE users_by_email(
  id UUID,
  email text PRIMARY KEY,
  username text,
);

然后，只需通过电子邮件地址查询该表。

Then, simply query that table by email address.

> SELECT id, email, username FROM users_by_email WHERE email='[e-mail]';

 id                                   | email                  | username
--------------------------------------+------------------------+----------
 d8e57eb4-c837-4bd7-9fd7-855497861faf | [e-mail] |      Mal

(1 rows)

这篇关于cassandra - 如何执行表查询？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！