比较一下就明白了
SQL> select rownum,bbb from a2 order by bbb; ROWNUM BBB
--------- ----------
2 11
1 22
3 33
4 aaa
5 aaa
6 aaa
7 bbb
8 bbb
9 bbb
10 ccc
11 ccc
12 ccc
13 ddd
14 ddd
15 eee已选择15行。SQL> select rownum,bbb from (select bbb from a2 order by bbb); ROWNUM BBB
--------- ----------
1 11
2 22
3 33
4 aaa
5 aaa
6 aaa
7 bbb
8 bbb
9 bbb
10 ccc
11 ccc
12 ccc
13 ddd
14 ddd
15 eee已选择15行。
SQL> select rownum,bbb from a2 order by bbb; ROWNUM BBB
--------- ----------
2 11
1 22
3 33
4 aaa
5 aaa
6 aaa
7 bbb
8 bbb
9 bbb
10 ccc
11 ccc
12 ccc
13 ddd
14 ddd
15 eee已选择15行。SQL> select rownum,bbb from (select bbb from a2 order by bbb); ROWNUM BBB
--------- ----------
1 11
2 22
3 33
4 aaa
5 aaa
6 aaa
7 bbb
8 bbb
9 bbb
10 ccc
11 ccc
12 ccc
13 ddd
14 ddd
15 eee已选择15行。
先执行select bbb from a2 order by bbb,排序后再显示行号
或是rank()函数呢