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From "Daniel John Debrunner (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-4) "order by" is not supported for "insert ... select"
Date Thu, 17 May 2007 16:31:18 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12496611
] 

Daniel John Debrunner commented on DERBY-4:
-------------------------------------------

> The point of this feature is to allow the user to ensure that, *if the rows are
> later selected and ordered by the auto-generated column*, then they will
> appear in the same order as they appeared during the INSERT. 

Once/if Derby supports the cycle option of identity columns  (CYCLE) then this would no longer
be guaranteed,
so any documentation should clearly indicated the restricted cases where such a guarantee
would apply.
(assuming of course the feature is accepted)

> "order by" is not supported for "insert ... select"
> ---------------------------------------------------
>
>                 Key: DERBY-4
>                 URL: https://issues.apache.org/jira/browse/DERBY-4
>             Project: Derby
>          Issue Type: New Feature
>          Components: SQL
>            Reporter: Christian d'Heureuse
>         Assigned To: Bryan Pendleton
>            Priority: Minor
>         Attachments: insertOrderBy.diff
>
>
> When filling a table with "insert ... select ...", "order by" cannot be specified.
> There is not method to copy a table sorted into another table (except using export/import).
This would be useful to optimize performance for big tables, or to create identity values
that are ascending (related to another column).
> Example:
> create table temp1 (
>    s varchar(10));
> insert into temp1 values 'x','a','c','b','a';
> create table temp2 (
>    i integer not null
>       generated always as identity
>       primary key,
>    s varchar(10));
> insert into temp2 (s)
>    select s from temp1 order by s;
> --> Error: "order by" is not allowed.
> -- trying to use "group by" instead of "oder by":
> insert into temp2 (s)
>    select s from temp1 group by s;
> select * from temp2;
> --> "group by" did not sort the table.

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