Need to generate n rows based on a value in a column

I'll assume

1. MyRef etc is a column in TableA
2. You have a numbers table

Something like:

SELECT * INTO #TableA
FROM
 (
    SELECT  1 AS ID, 3 AS QUANTITY, 'MyRef' AS refColumn
    UNION ALL
    SELECT 2, 2, 'AnotherRef'
) T


;WITH Nbrs ( Number ) AS (
    SELECT 1 UNION ALL
    SELECT 1 + Number FROM Nbrs WHERE Number < 99
)
SELECT
   A.ID, A.refColumn + CAST(N.Number AS varchar(10))
FROM
   #TableA A
   JOIN
   Nbrs N ON N.Number <= A.QUANTITY

This would also do the trick. It uses recursion, creates a table with rows 1-100.

WITH NBR ( NUM ) AS (
    SELECT 1 UNION ALL
    SELECT 1 + NUM FROM NBR 
    WHERE NUM < 100
)
SELECT * into NUMBERS from NBR

This will create the number of rows you want, in SQL Server 2005+, though I'm not sure exactly how you want to determine what MyRef and AnotherRef should be...

WITH
  expanded
AS
(
  SELECT id, Quantity FROM myTable

UNION ALL

  SELECT id, Quantity - 1 FROM expanded WHERE Quantity > 1
)

SELECT
  *,
  ROW_NUMBER() OVER (ORDER BY id, Quantity) AS unique_ref
FROM
  expanded
ORDER BY
  id,
  Quantity