怎么找出表中不同字段字的重复数据

如表 
num1       num2       num3         num4 
1               2             3                 4 
5               6             7                 8 
9               10           11               12 
2               3             9               11 ---
id             num                type
1              1                   1
2              5                   1
3              9                   1
4              2                   1
5              2                   2
6              6                   2
7              10                  2
8              3                   2
9              3                   3
10             7                   3
11             11                  3
12             9                   3
13
14
15
16