Choose join or Concatenate?

[surajap123]

Hi,

I am not sure whether to use join or concatenate while building my data model.

As we know data with same key values are merged into a single row when we use join. So, selections made in list box show the data as associated in our qlikview objects.

But, concatenate appends the rows of one table to another, so due to this the association of data is lost, which we find when we make selections, say in list box.

-My question is why should we use concatenate, when it causes loss of data association?

-How to choose whether to go with join or concatenate, when I have requirement in hand?

Regards,

Suraj

[Yousef_Amarneh]

Read this tutorial

Understanding Join, Keep and Concatenate

[its_anandrjs]

Whole scenario is depends on you how you make a model depends on business logic if we say for concatenation.

1. When there is same table fields in a more than one table so qlikview normal concate that tables or we forced the concatenation and depends on scenario.

2. Join when we use there is unique key combination and result of any table is based on any type of join like Right,inner,left,outer here it is also depends on scenario of data model.

Hope this helps

Thanks & Regards

[surajap123]

Thanks Anand and Yousef for the information !!

Yousef Amarneh- I have already gone through the below link and have good understand of them.

     http://qlikviewnotes.blogspot.co.uk/2009/11/understanding-join-and-concatenate.html

As per the link above the author says that concatenate causes loss of data association, so I am wondering why I should go for concatenate.

I understand that join is used when there is key combination in both the tables. If there is no key combination, then I create one(using autonumber function), and then use join, so that I wont loose the data association. Do you think my understanding is correct?

Please provide me a scenario or a sample app, which explains why I should go with join or concatenate based on the requirement.

Thanks !!

Regards,

Suraj

[#5]

Hi Suraj,

I personally use join when I need additional columns to existing data sets in an existing Table. By concatenate additional data sets with maybe additional columns are added to an existing Table.

Regards,

Torsten

[#6]

Thanks for sharing the tutorial

[bharath28 · Accepted solution]

http://community.qlik.com/blogs/qlikviewdesignblog/2014/01/14/merging-data

Hi Suraj,

-You have to go with concatenate when there is structural symmetry between 2 tables ie when 2 tables have almost similar fields.

-If two tables have different fields and user selection on a field in one table should imply one or several fields in the other table, then you should link the table.

Please refer the blog for more info..

Regards,

Bharath