Question

我想获得一行只包含表格中的非空值，可以从以下代码中复制：

select
  1 as unique_id,
  'null' as first,
  'second' as second,
  'null' as third
union all
select
  1 as unique_id,
  'first' as first,
  'null' as second,
  'null' as third
union all
select
  1 as unique_id,
  'null' as first,
  'null' as second,
  'third' as third

Answer 1

提供的代码的输出（假设'null'应为NULL）是：

1, 'first', NULL, NULL
1, NULL, 'second', NULL
1, NULL, NULL, 'third'

通过'merge'，我假设你想要输出看起来像：

1, 'first', 'second', 'third'

这可以通过以下方式完成：

SELECT MAX(first), MAX(second), MAX(third) FROM ... GROUP BY unique_id

当然，这假设您每个unique_id只出现一次值。您可以类似地使用其他函数，例如MIN或LISTAGG - 它们只需要排除NULL值。

在Redshift中合并多行非空值

1 个答案: