Concatenate strings from a column into a single row

Question

I am trying to string values from a column into a single row. I need a list of students (one row per student) with their phone number and they could have more than one number. I found a function that should do what I need but the syntax is for SQL Server, not SQL*Plus. I've tried several variations but can not come up with the correct syntax.
This is the SQL Server version:
CREATE FUNCTION dbo.GetPhoneList(@StudentID int)
RETURNS varchar(500) AS
BEGIN
DECLARE @StringList varchar(500)
SELECT @StringList = COALESCE(@StringList + ‘, ‘, ”) + Telephone.PhoneNumber
FROM Telephone t
WHERE t.StudentID = @StudentID
IF @StringList IS NULL
SET @StringList = ‘No Phone’
RETURN @StringList
END
SQL*Plus does not like the @ symbol, so I tried taking that out. I've put semi-colons where I think they should be, but I still get various error messages. Any suggestions?
Thanks.

Answer 1

Hi,
What you want to do is called "String Aggregation"
You could write a PL/SQL funcrtion to do that for a specific column in a specific table, but [this page|http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:2196162600402] has a couple of different generic solutions that will work on any tables and columns.
I recommend the first soluton, the user-defined function STRAGG, which you can copy from that page.
Once you have STRAGG installed, your query can be something like:
SELECT     s.student_id
,     NVL ( STRAGG (t.phone_number)
         , 'No phone'
         )     AS phone_nums
FROM          student          s
LEFT OUTER JOIN     telephone     t     ON s.student_id     = t.student_id
GROUP BY     s.student_id;On Oracle 10 (and up) you may have a similar function, WM_CONCAT (owned by WMSYS), already installed.
WM_CONCAT is not documented, so you may not want to use it in your Production applications.
It lokks like
Edited by: Frank Kulash on Feb 10, 2009 6:31 PM