eclipse - BIRT Mathematics on data set -

i pretty new birt reporting, can make simple charts , tables, bet when comes calculation of values data sets - have no clue in direction should watch.

for example have simple data set:

 count1   count2   max   type   lenght 616      3858     21    steel    20 723      4432     14    steel    40 854      5869     21         20 838      5225     14         40 

and have birt calculate approximately this:

sum(count2)/sum(count1)  type=all

so this

((5869+5225)/(854+838))

my question how there. @ point think need right direction how these kind of operations made.

thanks in advance.

i presume want display value somewhere on report, @ bottom of table data presented. if case add aggregation data element footer of table data displayed. in aggregation data element have opportunity specify expression sum(count2) , filter condition [type=all]. can division in data element.

if want compute value described you sql, i.e. select sum(count2)/sum(count1) mytable type='all'. have provide data report data source in form of excel spreadsheet, *.csv, database connection, etc.

so there few ways depending on requirements are.