sql - BigQuery - 连接谓词中不支持带表的子查询

Question

最近我开始从事 BigQuery 工作，但有些事情仍然让我感到困惑。 Big Query 上的此查询的替代方案是什么？

select a.abc, c.xyz
from table1 as a
left join table2 as c
on a.abc = c.abc
and c.date = (select t.date from table3 t)

问题是 Big Query 不支持连接中的子查询。我尝试了很多替代方案，但结果彼此不匹配。

Answer 1

假设 table3.date 是唯一的，请尝试编写如下查询:

select a.abc, c.xyz
from table1 a left join
     (table2 c join
      table3 t
      on c.date = t.date
     )
     on a.abc = c.abc;

如果table3中有重复项，您可以将其表述为:

select a.abc, c.xyz
from table1 a left join
     (table2 c join
      (select distinct date
       from table3 t
      ) t
      on c.date = t.date
     )
     on a.abc = c.abc;