How to get the max of row number for a table in teradata?

Question

Heading

MAX(ROW_NUMBER) does not work in teradata . But in cases where where it is required to implement the same scenario, how to achieve that?

Suppose my base table looks like this--

Month  Prev_Sport  Curr_Sport 
JAN     REST        CRICKET
JAN     CRICKET     RUGBY
FEB     REST        SKATING
FEB     SKATING     RAFTING
MAR     REST        RACING
MAR     RACING      GLIDING

The output table should be like--

Month   First_Sport    Last_Sport
JAN      CRICKET        RUGBY
FEB      SKATING        RAFTING
MAR      RACING         GLIDING

Here we can get the desired Last_Sport column in output if we create rownumber on main table and fetch the data based on the max(rownumber) . But the same does not work in teradata .

Is there any alternative solution for that?

Answer 1

No existing DBMS allows a MAX(ROW_NUMBER).

You didn't show how the ROW_NUMBER is calculated, but when you want the MAX of it you can simply reverse the ORDER and then

QUALIFY ROW_NUMBER() OVER (PARTITION BY ... ORDER BY .... DESC) = 1