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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-4284) All Columns become Nullable when Using left join
Date Fri, 28 Aug 2009 14:09:59 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4284?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12748825#action_12748825
] 

Knut Anders Hatlen commented on DERBY-4284:
-------------------------------------------

JoinNode.buildRCL() correctly makes all the columns from the right side of the join nullable
in a left outer join, and leaves the nullability of the columns on the left side untouched.
However, this code in SelectNode.bindResultColumns() later marks all the columns as nullable:

		/* Fix nullability in case of any outer joins in the fromList */
		if (fromList.hasOuterJoins())
			resultColumns.setNullability(true);

I'm running tests now to see if just removing the code causes any problems. Removing it does
give the expected nullability for the query in the description (name non-nullable, model nullable,
plat_no nullable).

> All Columns become Nullable when Using left join
> ------------------------------------------------
>
>                 Key: DERBY-4284
>                 URL: https://issues.apache.org/jira/browse/DERBY-4284
>             Project: Derby
>          Issue Type: Bug
>          Components: JDBC, SQL
>    Affects Versions: 10.5.1.1
>         Environment: Microsoft Windows XP SP3, Sun JDK 6 Update 14
>            Reporter: Chua Chee Seng
>         Attachments: Main.java
>
>
> Consider following:-
> create table person (
>   id varchar(20) not null,
>   name varchar(100) not null
> );
> create table car (
>   id varchar(20) not null,
>   person_id varchar(20) not null,
>   model varchar(100) not null,
>   plat_no varchar(100) not null
> );
> When select :-
> select
> p.name,
> c.model,
> c.plat_no
> from person p
> left join car c on (p.id = c.person_id);
> From the ResultSet, get the ResultSetMetaData and inspect each column's isNullable()
value, which is always = 1 (always nullable).  Expected : column 'p.name' isNullable = 0 (not
nullable), but I get 'p.name' isNullable = 1 (nullable)

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