T-sql Reset Row number on Field Change

Question

Similar to a recent post of mine \"t-sql sequential duration\"”, but not exactly the same, I want to reset the row number based on a change in column x (in my case, column \

Answer 1

The only solution I can think of is to use a cursor (ugh) and suffer through the RBAR process. NOT an elegant solution as the cursor will have to read in excess of 1m rows. Bummer.