Creating a string with hiearchical data

Question

This is being done in Crystal 8 will all updates applied.
I have a database with records that are linked to a series of "folders" that are hierarchical in nature as shown below:
Folder 1:
     Folder 1.1
          Folder 1.1.1
Folder 2
    Folder 2.1
All of the folders can have data records attached to them.
The database represents the folder structure in a table with the following attributes:
Folder ID   (integer)
Folder Name (String)  (such as "Folder 1"
Folder Parent ID (integer)
(other non-related fields)
If the folder is at the root level, then the value in Folder Parent ID is 0, otherwise, it is the Folder ID of the parent folder.
I need to be able to create a string field that displays the path for any given folder that I can insert into a group header or footer, or into a report header if the report deals with records in a single folder.  Desired format for the  string is: 
"Folder 1> Folder 1.1> Folder 1.1.1"
I need to be able to display at least 6 levels of folder indentation.
I have tried several ways to create a formula that will reliably produce the desired string, and can get close, but cannot completely address the problem.  My most successful approach was to put multiple instance of the table into the report and link the Folder Parent ID of one level to the Folder ID of the next level down and then use the data to build the string with a formula like this:
Local StringVar Result := {portfolio_master.portfolio_name};
local stringvar ExitLoop := "1" ;
if  ExitLoop = "1" then
    Result := {portfolio_master_1.portfolio_name} + "> " + Result
else
    ExitLoop := "0";
if {portfolio_master_1.parent_id} NE 0 AND ExitLoop = "1" then  // NE replaces Crystal not equal symbol which will not show
    Result := {portfolio_master_2.portfolio_name} + "> " + Result
else
    ExitLoop := "0";
if {portfolio_master_2.parent_id} NE 0 and ExitLoop = "1" then
    Result := {portfolio_master_3.portfolio_name} + "> " + Result
else
    ExitLoop := "0";
if {portfolio_master_3.parent_id} NE 0 and ExitLoop = "1" then
    Result := {portfolio_master_4.portfolio_name} + "> " + Result
else
    ExitLoop := "0";
if {portfolio_master_4.parent_id} NE 0 and ExitLoop = "1" then
    Result := {portfolio_master_5.portfolio_name} + "> " + Result
else
    ExitLoop := "0";
Result;
This formula works so long as the folder in question is exactly 5 levels deep.  Changing the nature of the links(inner join, left outer join etc.) between the instances of the table in the Database Expert changes the data that is visible, but I can't find a combination that will show ALL of the needed information for all of the folders. 
I understand that this is a brute force approach, and that there must be a different way to skin the cat.  My preference would be to "walk the tree" with a loop structure, but I don't see any way to do the needed data look up within the loop.
Any suggestions would be greatly appreciated!
Thanks,
L. Jasmann
Edited by: ljasmann1 on Jun 23, 2010 9:09 PM
Edited by: ljasmann1 on Jun 23, 2010 9:33 PM

Answer 1

I have been working to adapt the code provided above to my application.  Although I have worked with Crystal for quite a while, this is the first time that I have attempted to use SQL in Crystal... and it is just not working.. probably because I am no doing something very basic.
Here is  the code as currently set up in the SQL Formula Editor.  Only major difference from the code provided above is that the ID fields are integers instead of strings, and the field that I want to print out is a string field separate from the ID fields....  I have substituted the field names from the table I am referencing for the ones in the code above.  The table that I am using has been selected using the Database Expert.
DECLARE @Value int, @pf int, @FolderPath VarChar(MAX)
SET @Value = "portfolio_master"."portfolio_id"
SELECT @pf = "portfolio_master"."parent_id" FROM portfolio_master WHERE "portfolio_master"."portfolio_id" = @Value
SET @FolderPath = "portfolio_master"."portfolio_name"
WHILE @pf <> 0
BEGIN
SET @Value = @pf
SELECT @pf = "portfolio_master"."parent_id" FROM portfolio_master WHERE "portfolio_master"."portfolio_id" = @Value
SET @FolderPath = "portfolio_master"."portfolio_name" + ' > ' + @FolderPath
END
SELECT @FolderPath AS FolderPath
When I test the SQL statement it errors out on the very first statement (the DECLARE statement).  If I substitute a different statement in front of the DECLARE statement, it errors on that statement.
Here is the error that I get back. The database is using MS SQL Server.
Error in compiling SQL Expression:
Failed to retrieve data from the database.
Details:  ADO Error Code:  0x80040e14
Source:  Microsoft OLE db Provider for SQL Server
Description:  Incorrect syntax near the keyword u2018DECLAREu2019,
SQL State:  42000
Native Error:  156 [Database Vendor Code:  156].
Any pointers would be greatly appreciated...
Thanks,
Larry Jasmann