topic Re: Automatic join questioning in QlikView

Automatic join questioning

hillrunner — Sat, 07 Nov 2020 23:04:54 GMT

Hello, I have a question about joining two tables ( when we have a commun key )

When I let clikview does its automatic join for two tables ( so when i don't define join ), qlik doesn't create synthetic keys.

But when i define a join ( right,left...), it takes the whole table which i want to join with the left one and put all the fields as synthetic keys ( as i showed on photos )

But that's the same result at the end ( I mean with the results, I get, the first case is like an outer join )

so why is it different ? do i do the join badly ?

Thanks a lot for reading, if you could explain me why it is different in the schema it would be really kind 🙂 !

Re: Automatic join questioning

MayilVahanan — Sun, 08 Nov 2020 01:01:32 GMT

HI @hillrunner

Either you need to drop table tabEnfants on 42 line.
Or Mention the Left join in 31st line & remove the 40 & 41st line.

I.e. you are loading the table again and joining with NonPersonnes table. So the initial table(tabEnfants) also loaded and then same info joining with first table. That's the reason you're facing the synthetic key.

If you want to join, you can join directly, no need to load the table (tabEnfants) again. If you want to manipulate some info, then you can load the table again and drop the initial load info.

Re: Automatic join questioning

hillrunner — Sun, 08 Nov 2020 12:24:05 GMT

Ah yes i understand better thanks a lot ! There is only one thing left i don't really understand, it is when we let qlikview does the automatic join ( so when i don't explictely ask a join in the script )

It shows both tables in the table viewer, with a connection for the commun field, with no synthetic keys ( as showed in linked image ) What does qlik does in this case, it's not a join so ?

( because when i explictely ask a join [ and delete the temporary table or ask the join between table ], the two tables merge as a join should do )

Re: Automatic join questioning

MayilVahanan — Mon, 09 Nov 2020 02:31:39 GMT

HI @hillrunner

In Qlik, if 2 tables has common field name, it will create a link (Full Join) between both tables.
Even, if you are not use any join, it will have a link between 2 tables. and you can analysis between 2 tables information.

Re: Automatic join questioning

hillrunner — Wed, 11 Nov 2020 20:44:42 GMT

Ah ok thanks a lot i understand better why !