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https://issues.apache.org/jira/browse/CALCITE-4349?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17257665#comment-17257665
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Zhen Wang edited comment on CALCITE-4349 at 1/3/21, 6:57 AM:
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from my experiment, group_concat in mysql context does support multiple
expressions
[mysql example|https://www.db-fiddle.com/f/fouBy7MdxXzRmyzaWu8woB/2]
{code:sql}
CREATE TABLE test (
x int,
y char
);
INSERT INTO test (x, y) VALUES (1, 'a');
INSERT INTO test (x, y) VALUES (2, 'b');
select group_concat(x, y separator ';') from test;
--1a;2b
select
group_concat(deptno, ename order by ename) as combined_name
from emp;
{code}
list_agg function also supports this, but the `group_concat` query is
generating some incorrect code, which requires more time to fix.
- not use mysqlfunc will report function not found. this is verified. but not
sure where are such tests, I checked several mysql only function, didn't manage
to find such tests. guess the annotation is already quite intuitive itself.
I think I've addressed most of the comments.
as for many files are touched, it is really caused by the new syntax sugar
which is not supported before.
was (Author: zhenw):
from my experiment, group_concat in mysql context does support multiple
expressions
[mysql example|https://www.db-fiddle.com/f/fouBy7MdxXzRmyzaWu8woB/2]
{code:sql}
CREATE TABLE test (
x int,
y char
);
INSERT INTO test (x, y) VALUES (1, 'a');
INSERT INTO test (x, y) VALUES (2, 'b');
select group_concat(x, y separator ';') from test;
--1a;2b
select
group_concat(deptno, ename order by ename) as combined_name
from emp;
{code}
list_agg function also supports this, but the `group_concat` query is
generating some errors.
> Support GROUP_CONCAT aggregate function for MySQL
> -------------------------------------------------
>
> Key: CALCITE-4349
> URL: https://issues.apache.org/jira/browse/CALCITE-4349
> Project: Calcite
> Issue Type: Bug
> Reporter: Julian Hyde
> Assignee: Zhen Wang
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Support the {{GROUP_CONCAT}} aggregate function for MySQL. Here is the
> [syntax|https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_group-concat]:
> {noformat}
> GROUP_CONCAT([DISTINCT] expr [,expr ...]
> [ORDER BY {unsigned_integer | col_name | expr}
> [ASC | DESC] [,col_name ...]]
> [SEPARATOR str_val])
> {noformat}
>
> {{GROUP_CONCAT}} is analogous to {{LISTAGG}} (see CALCITE-2754) (and also to
> BigQuery and PostgreSQL's {{STRING_AGG}}, see CALCITE-4335). For example, the
> query
> {code:java}
> SELECT deptno, GROUP_CONCAT(ename ORDER BY empno SEPARATOR ';')
> FROM Emp
> GROUP BY deptno
> {code}
> is equivalent to (and in Calcite's algebra would be desugared to)
> {code:java}
> SELECT deptno, LISTAGG(ename, ';') WITHIN GROUP (ORDER BY empno)
> FROM Emp
> GROUP BY deptno
> {code}
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