[jira] Created: (JDO-637) JDOQL : Enhance the JDOQL with JOIN and ALIAS features

JDOQL : Enhance the JDOQL with JOIN and ALIAS features
-------------------------------------------------------

                 Key: JDO-637
                 URL: https://issues.apache.org/jira/browse/JDO-637
             Project: JDO
          Issue Type: New Feature
          Components: api2
            Reporter: Eric SULTAN


JOIN examples :
SELECT this.x, this,y, this.b.z FROM package.A JOIN this.b
SELECT this.x, this,y, this.b.z FROM package.A LEFT OUTER JOIN this.b

ALIAS examples :
SELECT alias1.x, alias1.y, alias1.b.z FROM package.A alias1 WHERE alias1.number > 10

JOIN and ALIAS examples :
SELECT alias1.x, alias1.y, alias1.b.z FROM package.A alias1 LEFT OUTER JOIN alias1.b WHERE alias1.number > 10
SELECT alias1.x, alias1.y, alias2.z FROM package.A alias1 LEFT OUTER JOIN alias1.b alias2 WHERE alias1.number > 10

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Andy Jefferson commented on JDO-637:
------------------------------------

Isn't the point supposed to be that JDOQL is Java syntax. Just adopting JPQL syntax doesn't seem to fit in with that goal to me. "INNER JOIN", "LEFT OUTER JOIN" don't mean a great deal for such as an XML datastore, or LDAP.
In general terms, when applying it to an RDBMS context, the type of relation and its nullability would define whether or not to use INNER JOIN or LEFT OUTER JOIN.

If wishing to use JPQL, any implementation can provide it using the same JDO API query mechanism (and some do).

> JDOQL : Enhance the JDOQL with JOIN and ALIAS features
> -------------------------------------------------------
>
>                 Key: JDO-637
>                 URL: https://issues.apache.org/jira/browse/JDO-637
>             Project: JDO
>          Issue Type: New Feature
>          Components: api2
>            Reporter: Eric SULTAN
>
> JOIN examples :
> SELECT this.x, this,y, this.b.z FROM package.A JOIN this.b
> SELECT this.x, this,y, this.b.z FROM package.A LEFT OUTER JOIN this.b
> ALIAS examples :
> SELECT alias1.x, alias1.y, alias1.b.z FROM package.A alias1 WHERE alias1.number > 10
> JOIN and ALIAS examples :
> SELECT alias1.x, alias1.y, alias1.b.z FROM package.A alias1 LEFT OUTER JOIN alias1.b WHERE alias1.number > 10
> SELECT alias1.x, alias1.y, alias2.z FROM package.A alias1 LEFT OUTER JOIN alias1.b alias2 WHERE alias1.number > 10

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Craig Russell commented on JDO-637:
-----------------------------------

+1 to what Andy says.

Simple cases don't even need any special syntax. The first example can be written as SELECT this.x, this,y, this.b.z FROM package.A where this.b != null.

Additionally, JDOQL already has the capability of joining persistent classes, using the variable syntax described in 14.6.5. The variables allow joining based on persistent fields that describe the relationships.

Inner versus outer joins are distinguished based on whether the reference is null or not. The default for JDOQL is "outer join" semantics. If you want "inner join" semantics, disallow null values. For example, you can join Employee and Department even if an Employee has no Department, but you can restrict Employees to those with Department references by using e.dept != null in the query.

> JDOQL : Enhance the JDOQL with JOIN and ALIAS features
> -------------------------------------------------------
>
>                 Key: JDO-637
>                 URL: https://issues.apache.org/jira/browse/JDO-637
>             Project: JDO
>          Issue Type: New Feature
>          Components: api2
>            Reporter: Eric SULTAN
>
> JOIN examples :
> SELECT this.x, this,y, this.b.z FROM package.A JOIN this.b
> SELECT this.x, this,y, this.b.z FROM package.A LEFT OUTER JOIN this.b
> ALIAS examples :
> SELECT alias1.x, alias1.y, alias1.b.z FROM package.A alias1 WHERE alias1.number > 10
> JOIN and ALIAS examples :
> SELECT alias1.x, alias1.y, alias1.b.z FROM package.A alias1 LEFT OUTER JOIN alias1.b WHERE alias1.number > 10
> SELECT alias1.x, alias1.y, alias2.z FROM package.A alias1 LEFT OUTER JOIN alias1.b alias2 WHERE alias1.number > 10

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Eric SULTAN commented on JDO-637:
---------------------------------

I understand what you mean.

Do I have to close this issue ?

> JDOQL : Enhance the JDOQL with JOIN and ALIAS features
> -------------------------------------------------------
>
>                 Key: JDO-637
>                 URL: https://issues.apache.org/jira/browse/JDO-637
>             Project: JDO
>          Issue Type: New Feature
>          Components: api2
>            Reporter: Eric SULTAN
>
> JOIN examples :
> SELECT this.x, this,y, this.b.z FROM package.A JOIN this.b
> SELECT this.x, this,y, this.b.z FROM package.A LEFT OUTER JOIN this.b
> ALIAS examples :
> SELECT alias1.x, alias1.y, alias1.b.z FROM package.A alias1 WHERE alias1.number > 10
> JOIN and ALIAS examples :
> SELECT alias1.x, alias1.y, alias1.b.z FROM package.A alias1 LEFT OUTER JOIN alias1.b WHERE alias1.number > 10
> SELECT alias1.x, alias1.y, alias2.z FROM package.A alias1 LEFT OUTER JOIN alias1.b alias2 WHERE alias1.number > 10

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     [ https://issues.apache.org/jira/browse/JDO-637?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Craig Russell closed JDO-637.
-----------------------------

    Resolution: Invalid

This does not appear to be an issue.

> JDOQL : Enhance the JDOQL with JOIN and ALIAS features
> -------------------------------------------------------
>
>                 Key: JDO-637
>                 URL: https://issues.apache.org/jira/browse/JDO-637
>             Project: JDO
>          Issue Type: New Feature
>          Components: api2
>            Reporter: Eric SULTAN
>
> JOIN examples :
> SELECT this.x, this,y, this.b.z FROM package.A JOIN this.b
> SELECT this.x, this,y, this.b.z FROM package.A LEFT OUTER JOIN this.b
> ALIAS examples :
> SELECT alias1.x, alias1.y, alias1.b.z FROM package.A alias1 WHERE alias1.number > 10
> JOIN and ALIAS examples :
> SELECT alias1.x, alias1.y, alias1.b.z FROM package.A alias1 LEFT OUTER JOIN alias1.b WHERE alias1.number > 10
> SELECT alias1.x, alias1.y, alias2.z FROM package.A alias1 LEFT OUTER JOIN alias1.b alias2 WHERE alias1.number > 10

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