Tableau - Conditions on LOD Expression -

i have purchase_log table has following fields:

uid, date, category, amount

and know first , second purchases dates each user of each category.

for example:

+-----+------+----------+--------+  | uid | date | category | amount | +-----+------+----------+--------+ |   | d1   | c1       | 100    | |   | d2   | c2       | 200    | |   | d3   | c1       | 120    | |   | d4   | c2       | 300    | +-----+------+----------+--------+ 

for above user records, first purchase category c1 made on date d1, , second purchase category c1 made on date d3.

i created 3 calculated fields:

• 1st purchase:

  { fixed [uid] : min([date])} 

• repeat purchase:

  iif([date]>[1st purchase],[date],null) 

• 2nd purchase:

  { fixed [uid] : min([repeat purchase])} 

but since there no distinction between categories, i'm not able see dates respect categories.

how should solve problem?

thanks.

you can loding on both uid , category.

• 1st purchase:

  { fixed [uid],[category] : min([date])} 

• repeat purchase:

  { fixed [uid],[category]: iif([date]>[1st purchase],[date],null)} 

• 2nd purchase:

  { fixed [uid],[category] : min([repeat purchase])}