Source data has detail records that are ordered by the header record
HeaderId
DetailId
Row 1
AAA
1234
Row 2
AAA
2345
Row 3
AAA
3456
Row 4
BBB
2345
Row 5
BBB
3453
Row 6
BBB
2587
Row 7
BBB
989
I need to get a incremental row count for each grouping, resetting to 1 for each group and looking for a solution.
HeaderId
DetailId
Seqnum
Row 1
AAA
1234
1
Row 2
AAA
2345
2
Row 3
AAA
3456
3
Row 4
BBB
2345
1
Row 5
BBB
3453
2
Row 6
BBB
2587
3
Row 7
BBB
989
4