有意思的SQL案例1

如下两个表

Table 1
==============
fn_a1    fn_a2
==============
A      3
B      1
C      2
--------------

Table 2
======================
fn_b1  fn_b2  fn_b3
======================
1      A      A1
2      B      B1
----------------------

结果
======================================
fn_a1  fn_a2  fn_b1  fn_b2  fn_b3
======================================
A      3     1      A1         1
A      3                       2
A      3                       3
B      1     2      B1         1
C      2                       1
C      2                       2
--------------------------------------

提问：
使用 Table 1,Table 2 ，求得如下结果集

SELECT a.fn_a1
     , a.fn_a2
     , b.fn_b1
     , b.fn_b2
     , c.lv fn_b3
  FROM Table_1 a
 INNER JOIN (SELECT 1 lv
             UNION ALL SELECT 2
             UNION ALL SELECT 3
             UNION ALL SELECT 4
             UNION ALL SELECT 5
             UNION ALL SELECT 6
             UNION ALL SELECT 7
             UNION ALL SELECT 8
             UNION ALL SELECT 9
             ) c
    ON a.fn_a2 >= c.lv
  LEFT OUTER JOIN Table_2 b
    ON a.fn_a1 = b.fn_b2
   AND c.lv = 1
 ORDER BY a.fn_a1, c.lv
;