oracle-统计---=sql comp

SQL>SELECT * FROM T;

A B C TITLE
---------- ---------- ---------- ----------
1 10 11 bj
1 20 21 tj
1 10 15 sh
2 5 7 bj
2 4 8 tj
2 3 9 sh

已选择6行。

已用时间: 00: 00: 00.00
SQL>select TITLE,
2 decode(TITLE, null, '', a) a,
3 decode(TITLE, null, 'sum ' || sum(b), sum(b)) b,
4 decode(TITLE, null, 'sum ' || sum(c), sum(c)) c
5 from t
6 group by a, ROLLUP(TITLE);

TITLE A B C
---------- ---------- ---------- ----------
bj 1 10 11
sh 1 10 15
tj 1 20 21
sum 40 sum 47
bj 2 5 7
sh 2 3 9
tj 2 4 8
sum 12 sum 24

已选择8行。

已用时间: 00: 00: 00.00

select sno,sname,class,mgrade
from students
order by class
computer avg(mgrade) by class