[jira] Created: (DERBY-6) Trigger of the form: create trigger ... values myFunction(); has no effect.

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  A new issue has been created in JIRA.

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View the issue:
  http://issues.apache.org/jira/browse/DERBY-6

Here is an overview of the issue:
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        Key: DERBY-6
    Summary: Trigger of the form: create trigger ... values myFunction(); has 
no effect.
       Type: Bug

     Status: Unassigned
   Priority: Minor

    Project: Derby
 Components: 
             SQL
   Fix Fors:
             10.0.2.0
   Versions:
             10.0.2.0

   Assignee: 
   Reporter: Tulika Agrawal

    Created: Mon, 27 Sep 2004 5:37 PM
    Updated: Mon, 27 Sep 2004 5:37 PM

Description:
Reporting for Jack Klebanoff, filed on derby-dev list.

> Jack Klebanoff wrote:
>
> | I would like to submit a fix for a bug in triggers.
> |
> | The bug is that a trigger of the form:
> |  create trigger ... values myFunction();
> | has no effect. MyFunction is not called even if the trigger is fired.
> | Side effects of myFunction do not happen. Derby does not allow a "CALL"
> | statement inside a trigger action so a values statement is the only way
> | to call a function/procedure in a trigger action.
> |
> | The cause of the bug is that since the values are not actually used by
> | the trigger, the trigger code does not fetch the row(s) returned by the
> | trigger action. The fix is simple: change class
> | org.apache.derby.impl.sql.execute.GenericTriggerExecutor to fetch (and
> | discard) the rows returned by a trigger action.
> |
> | Please review the change. The diff file is attached.
>
>
> I think you need to close the ResultSet (rs). Other locations in the
> code where a ResultSet is processed terminate with an rs.close(). Eg.
> see DeleteCascadeResultSet, ConstraintConstantAction.
>
> Dan.
>
I changed the code to close the ResultSet. The diff file is attached.

Jack
Index: java/engine/org/apache/derby/impl/sql/execute/GenericTriggerExecutor.java
===================================================================
--- java/engine/org/apache/derby/impl/sql/execute/GenericTriggerExecutor.java   
         (revision 37092)
+++ java/engine/org/apache/derby/impl/sql/execute/GenericTriggerExecutor.java   
         (working copy)
@@ -157,7 +157,18 @@
                                                 */
                                                 try
                                                 {
-                                                                
ps.execute(spsActivation, false, false, false);
+                                                                ResultSet rs = 
ps.execute(spsActivation, false, false, false);
+                if( rs.returnsRows())
+                {
+                    // Fetch all the data to ensure that functions in the 
select list or values statement will
+                    // be evaluated and side effects will happen. Why else 
would the trigger action return
+                    // rows, but for side effects?
+                    // The result set was opened in ps.execute()
+                    while( rs.getNextRow() != null)
+                    {
+                    }
+                }
+                rs.close();
                                                 } 
                                                 catch (StandardException e)
                                                 {


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