topic Re: when to use concatenate vs join, trigger to decide in QlikView

when to use concatenate vs join, trigger to decide

userid128223 — Thu, 30 Jan 2014 05:26:22 GMT

I understand the basic difference between concatenate and join. however I get confused as to which one to use in what situation.

can someone please give easy example when you will use 1 vs the other, what triggers that decision. So if you are evaluating and comming up with data model, what aha moment will say use concatenate vs join or vice versa.

Re: when to use concatenate vs join, trigger to decide

tresB — Thu, 30 Jan 2014 05:32:28 GMT

There are some very good community stuffs like : http://community.qlik.com/blogs/qlikviewdesignblog/2012/09/12/to-join-or-not-to-join

and CONCATENATE vs JOIN

you should look into.

Re: when to use concatenate vs join, trigger to decide

maneshkhottcpl — Thu, 30 Jan 2014 05:37:23 GMT

Let Table A

ID, Name

1, X

2, Y

Table B

ID, Gender

1, M

2, F

3, M

If you

Load A

Concatenate

Load B

then Output will be

ID, Name, Gender

1, X, -

2, Y, -

1, -, M

2, -, F

3, -, M

as concatenate appends the rows so for ID 1 and 2 Gender is null as no Gender is table A

now second scenario

Load A

Left Join

Load B

Out put

ID, Name, Genjder

1, X, M

2, Y, F

as join add entity to existing table i.e A or B

Regards

Manesh