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https://issues.apache.org/jira/browse/CALCITE-7331?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18044811#comment-18044811
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Zhen Chen commented on CALCITE-7331:
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[~julianhyde] Thank you so much for your detailed and comprehensive questions.
These things should indeed have been done sooner, which would have saved you a
lot of time. I apologize for that. I have provided answers to each question,
although these might actually be in CALCITE-7310, but since you replied here,
I've answered them in this Jira. Please check if this meets your needs.
{quote}You should link to the case where we added EXCLUDE.
{quote}
I have linked the CALCITE-7310
{quote}Include at least one example.
{quote}
In CALCITE-7310 , We can support following:
{code:java}
SELECT * EXCLUDE(deptno, empno) FROM emp; // ok
SELECT * EXCLUDE(deptno, empno, empno) FROM emp; // ok, empno will be
deduplicated
SELECT emp.* EXCLUDE(emp.deptno, emp.empno) FROM emp; // ok, support sql
identifier
SELECT * EXCLUDE(deptno, foo) FROM emp; // failed{code}
{quote}Clickhouse supports "SELECT expr EXCEPT ()", not just "SELECT * EXCEPT".
The description should say exactly what we support.
{quote}
Similar to the implementation in ClickHouse, but the expr in <expr>
EXCEPT(col1, col2) only supports *.
{quote}Is the syntax ambiguous? "SELECT 1 AS x, 2 AS y EXCEPT (x)" is very
similar to "SELECT 1 AS x, 2 AS y EXCEPT (SELECT 1, 3)"
{quote}
To avoid confusion, EXCLUDE only supports columns and does not support SELECT
clauses.
{quote}Which config option(s) control this? Is it enabled by default?
{quote}
Since this syntax is not in the SQL specification, it is only enabled in Babel
and disabled in Core. This feature can be enabled using *includeStarExclude:
true* (in the config.fmpp file).
{quote}Do you give an error if EXCEPT references columns that don't exist?
{quote}
Yes, see the example above please.
{quote}Do you give an error if EXCEPT has duplicates?
{quote}
No, It will automatically remove duplicates.
{quote}Do you give an error if, after applying EXCEPT, there are zero columns?
{quote}
Yes, it will throw an error.
> Support the alias form SELECT * EXCEPT() for SELECT * EXCLUDE()
> ---------------------------------------------------------------
>
> Key: CALCITE-7331
> URL: https://issues.apache.org/jira/browse/CALCITE-7331
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.41.0
> Reporter: Zhen Chen
> Assignee: Zhen Chen
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.42.0
>
>
> Based on the CALCITE-7310 implementation, this Jira primarily serves as an
> alias extension. For example:
> SELECT * EXCLUDE(deptno, empno) FROM emp;
> Similarly, it can be written as:
> SELECT * EXCEPT(deptno, empno) FROM emp;
> Similar to the implementation in ClickHouse[1], but the expr in <expr>
> EXCEPT(col1, col2) only supports *.
> [1]
> [https://clickhouse.com/docs/zh/sql-reference/statements/select/except-modifier]
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