IF DUPLICATE ENTRIES?

[kallmund]

sorry.....
ich hab die < falsch gesetzt!... also nochmal

id | a | b | block
1  | 1 | 1 | 1
2  | 2 | 1 | 1
3  | 1 | 2 | 1
4  | 2 | 2 | 1
5  | 1 | 3 | 1 <
6  | 2 | 3 | 1 <
7  | 1 | 4 | 2
8  | 2 | 4 | 2
9  | 1 | 5 | 2
10 | 2 | 5 | 2
11 | 1 | 3 | 2 <
12 | 2 | 3 | 2 <

kalli