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Date: Fri, 2 May 2008 11:16:55 -0700 (PDT)
From: "Daniel John Debrunner (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Commented: (DERBY-3652) Derby does not follow the SQL
 Standard when trying to map SQL routines to Java methods.
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    [ https://issues.apache.org/jira/browse/DERBY-3652?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12593838#action_12593838 ] 

Daniel John Debrunner commented on DERBY-3652:
----------------------------------------------

I would advise approach 1) I would guess there is no path to call the methods with the Integer signature.

> Derby does not follow the SQL Standard when trying to map SQL routines to Java methods.
> ---------------------------------------------------------------------------------------
>
>                 Key: DERBY-3652
>                 URL: https://issues.apache.org/jira/browse/DERBY-3652
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.5.0.0
>            Reporter: Rick Hillegas
>         Attachments: derby-3652-01-aa-mixTypesOnFirstPass.diff, derby-3652-01-ab-mixTypesOnFirstPass.diff, SignatureMapping.html, SignatureMapping.html, SignatureProblems.java, signatureProblems.sql
>
>
> I have only tested this in the 10.5 trunk. However, I suspect that this affects all previous releases of Derby as well.
> In resolving method signatures for function/procedure invocations, the SQL standard makes the following definitions in part 13, section 4.5 (parameter mapping). These definitions, in turn, refer to tables B-1 and B-3 in JDBC 3.0 Specification, Final Release, October 2001 ([JDBC]).
>     * Simply mappable - This refers to the correspondence of SQL and Java types described in [JDBC] table B-1. This is the table which defines the mapping of SQL types to Java primitives.
>     * Object mappable - This refers to the correspondence of SQL and Java types described in [JDBC] table B-3. This is the table which defines the mapping of SQL types to Java wrapper objects.
>     * Output mappable - For OUT and INOUT parameters, this refers to a single element array whose cell is simply mappable or object mappable. E.g. Integer[] or float[].
>     * Mappable - This means simply, object, or output mappable.
>     * Result set mappable - This means a single element array whose cell is a type which implements either java.sql.ResultSet or sqlj.runtime.ResultSetIterator.
> Putting all of this together, section 4.5 continues:
>     "A Java method with M parameters is mappable (to SQL) if and only if, for some N, 0 (zero) <= N <= M, the data types of the first N parameters are mappable, the last M - N parameters are result set mappable, and the result type is either simply mappable, object mappable, or void."
> Section 8.6 gives more detailed rules, but they are hard to follow. According to section 8.6, when resolving a routine invocation, Derby should expect to find one and only one static mappable method with the expected external name (Java class + method name).
> I believe that this is a fair description of the rules. This, at least, is what some other databases appear to do. See, for instance, http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.help.ase_15.0.java/html/java/java126.htm and http://www.service-architecture.com/database/articles/mapping_sql_and_java_data_types.html
> We do not have a regression test which verifies that Derby applies the SQL standard resolution rules. There may be several divergences from the standard. This JIRA is a place to track those discrepancies. Here is one that I have noticed:
> The following SQL signature
> ( a int ) returns int
> should be mappable to any of the following Java signatures
> public static int f( int a )
> public static int f( Integer a )
> public static Integer f( int a )
> public static Integer f( Integer a )
> However, I observe that Derby is only able to resolve the first and third signatures (the ones with primitive arguments). I will attach a test case showing this problem.
> I will also attach an html table summarizing the simply and object mappable rules.

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