您不需要内部连接到虚拟表或分析函数来生成行号；您可以只在表本身上使用connect by（及其对应的level函数），如下所示：

WITH tst_dim_ban_selected AS (SELECT 1 ban_key, 'a' cust_fullname, 3 n FROM dual UNION ALL
                              SELECT 2 ban_key, 'b' cust_fullname, 4 n FROM dual)
-- end of mimicking your table with data in it. See SQL below
SELECT db.ban_key,
       db.cust_fullname,
       LEVEL row_num
FROM   tst_dim_ban_selected db
CONNECT BY LEVEL <= db.n
           AND PRIOR db.ban_key = db.ban_key -- assuming this is the primary key
           AND PRIOR sys_guid() IS NOT NULL;

   BAN_KEY CUST_FULLNAME    ROW_NUM
---------- ------------- ----------
         1 a                      1
         1 a                      2
         1 a                      3
         2 b                      1
         2 b                      2
         2 b                      3
         2 b                      4

如果表的主键中除ban_key之外还有其他列，则需要确保它们包含在connect by子句的prior <column> = <column>s列表中。因此，connect by可以唯一地标识每一行，这意味着该行仅在该行上循环，而在其他行上则没有。在PRIOR sys_guid() IS NOT NULL需要防止CONNECT BY循环的发生。