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micheledenardi
Valued Contributor

Left Join Issue

Good afternoon community,

probably i'm more newbie as I think because until today I thought to knew qlik Joins but now I'm here with a question for you.

Is there anyone can expain me why CASE1 result is different from CASE2 ?

It seems that doing the left join from SampleTable loaded with * qlik consider only SampleTable1 table and not the others.

I don't think is this because the second and third SampleTable table loaded with * goes on autoconcatenate on Main Table before applying the join statement  because on MainTable table all data of SampleTable2 and SampleTable3 are missing...


I'd attach the example data i've used...

Case.png

1 Solution

Accepted Solutions

Re: Left Join Issue

The problem with the first case is that after the 1st left join, your MainTable have now a new field called Data. So now the join is not just on the Key field, but both Key and Data. And since the Key matches, but Data doesn't the join actually doesn't take place. You can check this by doing a Join instead of Left Join.

Case 2 works because, all the three excels are first concatenated before it gets left joined all at once.

Does that make sense?

View solution in original post

6 Replies
effinty2112
Honored Contributor

Re: Left Join Issue

Hi Michele,

This is interesting. I don't think I can explain other than take from this that it's necessary to complete the join table before we attempt to use in a join. Thanks for posting this!

Regards

Andrew

Re: Left Join Issue

The problem with the first case is that after the 1st left join, your MainTable have now a new field called Data. So now the join is not just on the Key field, but both Key and Data. And since the Key matches, but Data doesn't the join actually doesn't take place. You can check this by doing a Join instead of Left Join.

Case 2 works because, all the three excels are first concatenated before it gets left joined all at once.

Does that make sense?

View solution in original post

micheledenardi
Valued Contributor

Re: Left Join Issue

Yes, your reasoning has lot of sense !

Thanks !

Re: Left Join Issue

No problem at all

effinty2112
Honored Contributor

Re: Left Join Issue

Lovely explanation!

Re: Left Join Issue

Thanks Andrew