从雅典娜查询的两个桌子中创建景色

发布于 2025-01-28 09:24:43 字数 303 浏览 3 评论 0原文

基本上，我的用例是我在雅典娜中创建一个视图，但我想根据表中的一列给出的日期（snapshot_date）从两个表（snapshot_date）中选择数据。怎么做？我找不到该语法，因为

SELECT
 baseline_year
, marketplace
, locale
, snapshot_time
, ...
FROM
  table1

我想实现快照时间小于2022-05-01，然后使用表2，否则请使用表1。我们可以从任何形式的条件中加入吗？我已经探讨了我们可以在列上执行条件时使用case_，但不确定可以使用吗？

原文

Basically my use case is that I am creating a view in athena but i want to select the data from two tables depending on the date (snapshot_date) which is given by a column in the tables. How to do it? I am not finding the syntax for that

SELECT
 baseline_year
, marketplace
, locale
, snapshot_time
, ...
FROM
  table1

I want to achieve something like if snapshot time is less than 2022-05-01, then use table 2 otherwise use table 1.
Can we any kind of conditioning in FROM? I have explored that we can use CASE_WHEN for performing conditions on columns, but not sure that can be used in FROM?

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公布 2025-02-04 09:24:43

如果我没记错的话，如果SnapShot_Time早于2022-05-01，则应使用Table2，如果SnapShot_Time大于或等于2022-05-01 ，无论哪种shapshot_time 这两个桌子有。

SELECT ... FROM table1 where date(snapshot_time)>= '2022-05-01'
union
SELECT ... FROM table2 where date(snapshot_time) < '2022-05-01' ;

If I am not mistaken, you meant to use table2 if the snapshot_time is earlier than 2022-05-01 and use table1 if the snapshot_time is greater than or equal to 2022-05-01 REGARDLESS of what shapshot_time those two tables have.

SELECT ... FROM table1 where date(snapshot_time)>= '2022-05-01'
union
SELECT ... FROM table2 where date(snapshot_time) < '2022-05-01' ;

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心的位置 2025-02-04 09:24:43

您可以继续进行参数化视图，尝试创建一个函数：

CREATE FUNCTION func() RETURNS DATE
  RETURN @var;

然后创建视图：

CREATE VIEW view1 AS
SELECT
 T1.baseline_year
, T1.marketplace
, T1.locale
, T1.snapshot_time
, ...
FROM  table1 AS T1
WHERE DATE(T1.snapshot_time) >= func()
UNION
SELECT
 T2...,
 ..
FROM
  table1 AS T2
WHERE DATE(T2.snapshot_time) <= func()

You can proceed with a parametrized view, try to create a function:

CREATE FUNCTION func() RETURNS DATE
  RETURN @var;

Then create the view :

CREATE VIEW view1 AS
SELECT
 T1.baseline_year
, T1.marketplace
, T1.locale
, T1.snapshot_time
, ...
FROM  table1 AS T1
WHERE DATE(T1.snapshot_time) >= func()
UNION
SELECT
 T2...,
 ..
FROM
  table1 AS T2
WHERE DATE(T2.snapshot_time) <= func()

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