Oracle 11g Release 2

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CREATE TABLE My_SQL_table ( Site_NUM, start_week, end_week ) AS
SELECT 'France',  50, 52 FROM DUAL UNION ALL
SELECT 'Germany', 41, 43 FROM DUAL UNION ALL
SELECT 'USA',     12, 13 FROM DUAL;
3 rows affected

SELECT site_num,
       COLUMN_VALUE wks_inbtwn
FROM   My_SQL_table tbl1
       CROSS JOIN 
       TABLE(
         CAST(
           MULTISET(
             SELECT tbl1.START_WEEK + LEVEL
             FROM   DUAL
             CONNECT BY tbl1.START_WEEK + LEVEL <= tbl1.END_WEEK
           )
           AS SYS.ODCINUMBERLIST
         )
       )


SITE_NUM
WKS_INBTWN


France
51

France
52

Germany
42

Germany
43

USA
13


WITH rsqfc ( site_num, start_week, end_week ) AS (
  SELECT site_num, start_week + 1, end_week
  FROM   my_sql_table
UNION ALL
  SELECT site_num, start_week + 1, end_week
  FROM   rsqfc
  WHERE  start_week < end_week
)
SELECT site_num, start_week AS wks_inbtwn
FROM   rsqfc
ORDER BY site_num, wks_inbtwn


SITE_NUM
WKS_INBTWN


France
51

France
52

Germany
42

Germany
43

USA
13