[
https://issues.apache.org/jira/browse/DERBY-4374?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12753651#action_12753651
]
Knut Anders Hatlen commented on DERBY-4374:
-------------------------------------------
The description of the operation could say something similar to this (inspired
by the wording used in the other JOIN operators):
A CROSS JOIN is a JOIN operation that produces the Cartesian product of two
tables. Unlike other JOIN operators, it does not let you specify a join clause.
You may however specify a WHERE clause in the SELECT statement.
Examples that we may provide:
SELECT * FROM T1 CROSS JOIN T2
which is equivalent to
SELECT * FROM T1, T2
and
SELECT * FROM T1 CROSS JOIN T2 WHERE T1.X = T2.X
which is equivalent to
SELECT * FROM T1 INNER JOIN T2 ON T1.X = T2.X
And perhaps we should have a more complex example. For instance:
SELECT * FROM T1 LEFT OUTER JOIN T2 CROSS JOIN T3 ON T1.X = T2.X WHERE T3.Z > 50
We should probably change the examples so that they use the same table names as
the other JOIN examples.
> Document the CROSS JOIN operation in the reference manual
> ---------------------------------------------------------
>
> Key: DERBY-4374
> URL: https://issues.apache.org/jira/browse/DERBY-4374
> Project: Derby
> Issue Type: Improvement
> Components: Documentation
> Affects Versions: 10.6.0.0
> Reporter: Knut Anders Hatlen
>
> CROSS JOIN was added in DERBY-4355. We should document it alongside the other
> join operations in the reference manual.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
