Question

目标：我想使用“带有条款”来选择列表国家/地区。以下仅适用于选择一个国家/地区。

WITH parameters AS (SELECT 'Sweden' as Country) 
SELECT * 
FROM Countries_table 
WHERE Countries_table.Country = (SELECT Country FROM parameters)

我想做同样的事情，但要使用附带条款中的国家/地区列表。我尝试过类似的语法（但均无效）：

WITH parameters AS (SELECT ('Sweden', 'Norway', 'Finland') as Country)
SELECT * 
FROM Countries_table 
WHERE Countries_table.Country IN (SELECT Country FROM parameters)

和...

WITH parameters AS (SELECT ['Sweden', 'Norway', 'Finland'] as Country)
SELECT * 
FROM Countries_table 
WHERE Countries_table.Country IN (SELECT Country FROM parameters)

正确使用什么语法来实现带子句的列表，并将该列表传递给以下select语句？

列表中每个国家的结果应如下所示：

Country |    Town     | Population size
---------------------------------------
Sweden | Stockholm | 1 500 000

Answer 1

在Postgres中，您可以这样做：

WITH parameters (country) AS (
  values ('Sweden'), ('Norway'), ('Finland')
)
SELECT * 
FROM Countries_table 
WHERE Countries_table.Country IN (SELECT Country FROM parameters);

如果Redshift不支持该功能，则需要使用UNION

WITH parameters (country) AS (
  select 'Sweden' union all
  select 'Norway' union all
  select 'Finland'
)
SELECT * 
FROM Countries_table 
WHERE Countries_table.Country IN (SELECT Country FROM parameters);

有条款清单

1 个答案: