[jira] [Updated] (CALCITE-4305) Implicit column alias for single-column VALUES, and UNNEST of ARRAY and MULTISET constructors

["Julian Hyde (Jira)" <ji...@apache.org>]

     [ 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 VALUES, and UNNEST of ARRAY and MULTISET constructors  (was: Implicit column alias for single-column UNNEST and VALUES)

> Implicit column alias for single-column VALUES, and UNNEST of ARRAY and MULTISET constructors
> ---------------------------------------------------------------------------------------------
>
>                 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].
> As an extension to PostgreSQL and BigQuery, we also derive a column alias for UNNEST of single-column MULTISET and single-column VALUES. Examples:
> {code}
> SELECT f FROM UNNEST(MULTISET ['apple', 'banana', 'pear']) AS f;
> SELECT f FROM (VALUES 'apple', 'banana', 'pear') AS f;
> {code}



--
This message was sent by Atlassian Jira
(v8.3.4#803005)