create table gxg (sid int,var varchar(400));
insert into gxg 
select 104,'1a,2a,3a,'
union all
select 105,'1b,2b,3b,'
union all
select 106,'1c,'
union all
select 107,'';
--我想要的结果是:

104,1a,1
104,2a,2
104,3a,3
105,1b,1
105,2b,2
105,3b,3
106,1c,1
107,,1

SELECT   *
    FROM (SELECT SID, REGEXP_SUBSTR (var, '[^,]+', 1, d.l) var, l
            FROM gxg g,
                 (SELECT     LEVEL l
                        FROM DUAL
                  CONNECT BY LEVEL < 10) d
           WHERE REGEXP_SUBSTR (var, '[^,]+', 1, d.l) IS NOT NULL
          UNION ALL
          SELECT SID, NULL var, 1 l
            FROM gxg
           WHERE var IS NULL)
ORDER BY SID, l