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Posted to issues@calcite.apache.org by "Julian Hyde (Jira)" <ji...@apache.org> on 2020/10/24 07:11:00 UTC
[jira] [Updated] (CALCITE-4305) Implicit column alias for
single-column UNNEST and VALUES
[ https://issues.apache.org/jira/browse/CALCITE-4305?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Julian Hyde updated CALCITE-4305:
---------------------------------
Summary: Implicit column alias for single-column UNNEST and VALUES (was: Implicit column alias for single-column UNNEST)
> Implicit column alias for single-column UNNEST and VALUES
> ---------------------------------------------------------
>
> Key: CALCITE-4305
> URL: https://issues.apache.org/jira/browse/CALCITE-4305
> Project: Calcite
> Issue Type: Bug
> Reporter: Julian Hyde
> Assignee: Julian Hyde
> Priority: Major
>
> Single-column UNNEST with a single alias should assign that alias to both a table and the unique column. For example, PostgreSQL returns a column called 'unnest' in the first, and 'fruit' in all of the rest:
> {code}
> select * from UNNEST(array ['apple', 'banana', 'pear']);
> select * from UNNEST(array ['apple', 'banana', 'pear']) as fruit;
> select * from UNNEST(array ['apple', 'banana', 'pear']) as t(fruit);
> select t.* from UNNEST(array ['apple', 'banana', 'pear']) as t(fruit);
> select fruit.* from UNNEST(array ['apple', 'banana', 'pear']) as fruit;
> {code}
> Thus {{FROM UNNEST(...) AS x}} is creating a table alias {{x}} and a column alias {{x}}.
> This only happens for UNNEST. When aliasing other single-column relations the column name is retained, such as a SELECT-FROM-UNNEST sub-query as follows:
> {code}
> SELECT fruit.*
> FROM (SELECT * FROM UNNEST(array ['apple', 'banana', 'pear']) as x) as fruit;
> x
> ======
> apple
> banana
> pear
> {code}
> BigQuery has [similar behavior|https://cloud.google.com/bigquery/docs/reference/standard-sql/functions-and-operators#any_value].
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