How do you compare a row in sql to the previous row?

Asked Oct 04 '17 at 15:16

Active Oct 04 '17 at 16:25

Viewed 761 times

I have two rows of data, and would like to compare one row to itself before, for e.g.

x1, id1
y1, id2
z1, id3
z1a, id3

I'd like to add a third column comparing ID3 to ID2 so I can right a conditional to give me a list of 0's and 1's, like this

x1, id1, 0
x2, id1, 1
x3, id2, 0
x4, id3, 0
x5, id3, 1

Is there anyway to do this????

edited Oct 04 '17 at 16:25

asked Oct 04 '17 at 15:16

F123

2

please tag the RDBMS you're using. thanks – Esteban P. Oct 04 '17 at 15:17
there are analytics functions , like **lag** – Frank Oct 04 '17 at 15:17
in case you're using SQL Server, have a look here: https://learn.microsoft.com/en-us/sql/t-sql/functions/lag-transact-sql – Esteban P. Oct 04 '17 at 15:17
You could use inner join like in this: https://stackoverflow.com/questions/1890411/comparing-sql-table-to-itself-self-join – Ana Oct 04 '17 at 15:28

0 Answers0