Preparation:

1. Create a Date Picker Custom Field called Alternate Creation Date, set it to the project that you need to modify, and apply it to the Default Screen.
2. Browse to the issue you want to modify.
3. Click on Edit, look for the Alternate Creation Date field on the Edit Issue screen and set the desired created date on it.
4. Update the issue and check if the change has been applied.
   
5. Repeat this process to all the issues you want to modify.

Perform the database update:

1. Stop your JIRA application.

2. Execute the below SQL to perform the update. Repeat this step for every issue that requires updating.

   Click here to expand for JIRA 6.1 and higher...

   Replace the references to ABC with the project key and 123 with the issue number.

   UPDATE jiraissue
   SET    created = (SELECT datevalue
                 FROM   customfieldvalue
                 WHERE  issue = (SELECT id
                               FROM   jiraissue
                               WHERE  issuenum = '123'
                               AND    project = (SELECT id
                                             FROM   project
                                             WHERE  pkey = 'ABC')
                               AND    customfield = (SELECT id
                                             FROM   customfield
                                             WHERE  cfname LIKE 'Alternate Creation Date'))
                 where  issuenum = '123'
                 AND    project = (SELECT id
                               FROM   project
                               WHERE  pkey = 'ABC');

   This was tested on PostgreSQL and may require modifying based on the DBMS used. Please consult with your DBA on the appropriate syntax.

   Click here to expand for JIRA 6.1 and lower...

   Replace the ABC-123 for the issue key you want to modify.

   UPDATE jiraissue 
   SET    created = (SELECT datevalue 
                     FROM   customfieldvalue 
                     WHERE  issue = (SELECT id 
                                     FROM   jiraissue 
                                     WHERE  pkey = 'ABC-123') 
                            AND customfield = (SELECT id 
                                               FROM   customfield 
                                               WHERE 
                                cfname LIKE 'Alternate Creation Date')) 
   WHERE  pkey = 'ABC-123';

   This was tested on PostgreSQL and may require modifying based on the DBMS used. Please consult with your DBA on the appropriate syntax.

3. Start the application and perform a full reindex. This is required as the indexes for the created date will be out of sync with the database.

4. Check if the creation date has been changed, for example:
   
5. Remove the custom field Alternate Creation Date and the issue update will be complete.