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Hi Folks,
i got a Question: i find in the script the following part of concatenation of the table to the master calender, that i am not able to understand:
Qualify *;
MC1:
load
MC.Year as Year,
sum(MC.Day) as Day
resindent MasterCalenderTemp
ProjectTable:
join (MC1)
load
Project as MC1.Project
resident ProjectTable;
my Question or what i didnt understand in this case, is concatenation / join of table: ProjectTable to the Table: MC1. i thought i should concatenate my table with Master Calender on the base of data-fields, but in this case i dont have any datafields, only one field: Project.
can anybody explain my the logic of this concatenation to master calender.
Thanks a lot
Beck
Beck,
first of all this is a normal join() and not a concatenation. I suggest to you to read this article which shows the differences between joins and contanations: UNDERSTANDING JOIN AND CONCATENATE
Second there is some script missing on the first table, a "group by MC.Year;" is needed to use sum() on loads.
In this case the result of that join (where there are no key between that tables) is a cartesian product where all combinations of your first table will be joined to all combinations of your second table.
Sometimes this technique has sense in small dataset and for very very particular cases.
Hi Michele,
thanks a lot for your responce, i know what does the concatenate and join mean, my Question was about joining of one table with one field to master calender.
This depens from your analysis.
A cartesian product (result of that join) can be useful or useless, it depends from your datamodel and what you're analysing. Maybe you can use that join to have the total amout of days worked on each project in order to understand the weight/incidence of each project.
I'm sorry but is impossible to give you an answer about "Why" someone create that join without a sufficient knowledge of the analysis.
Hi Michele
thanks a lot for your time and help