I have a Budgets table with two columns:
BudgetID BudgetPath 1 HR 1 HRIT 1 Americas 2 HR 2 Staffing 3 IT 3 Finance 3 HR 3 Asia Pacific
Is it possible in T-SQL or PL/SQL to string together the values in BudgetPath, grouped by BudgetID, so the output would be:
BudgetID BudgetPath 1 HR>HRIT>Americas 2 HR>Staffing 3 IT>Finance>HR>Asia Pacific
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Sadly, there is nothing quite as elegant for T-SQL or PL/SQL as MySQL's wonderful GROUP_CONCAT function. The drop-dead simple solution using GROUP_CONCAT is:
select BudgetID
, group_concat(BudgetPath separator '>')
as BudgetPaths
from Budgets
group
by BudgetID
For Oracle, have a look at: Displaying multiple records in one row.
For T-SQL, here's a method that will work. First, create a temporary table like this:
create table TempBudgetPaths ( BudgetID integer not null primary key , BudgetPaths varchar(max) null )
Next, populate this table with keys:
insert
into TempBudgetPaths
( BudgetID )
select distinct
BudgetID
from Budgets
Finally, update the temporary table like this:
DECLARE @row INTEGER, @maxrows INTEGER
SELECT @row=1, @maxrows=count(*) FROM Budgets
WHILE @row <= @maxrows
BEGIN
UPDATE TempBudgetPaths
SET BudgetPaths
= COALESCE(t1.BudgetPaths+'>','')
+ t2.BudgetPath
FROM TempBudgetPaths t1
INNER
JOIN (
SELECT BudgetID
, BudgetPath
, ROW_NUMBER() OVER
( ORDER BY BudgetID
, BudgetPath )
as rownum
FROM Budgets
) AS t2
ON t2.BudgetID = t1.BudgetID
WHERE t2.rownum = @row
SELECT @row = @row + 1
END
SELECT * FROM TempBudgetPaths
Not nearly as pretty as GROUP_CONCAT, is it. Nevertheless, it works, and produces these results:
BudgetID BudgetPaths 1 Americas>HR>HRIT 2 HR>Staffing 3 Asia Pacific>Finance>HR>IT
Notice the sequence in which the BudgetPaths were appended. This is a result of the OVER (ORDER BY ...) clause. This is not the same as your sequence, which appears to be some kind of hierarchy. To achieve your sequence will require an additional data column, to indicate sequence of BudgetPath within BudgetID.
This was first published in August 2007
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