topic Re: When do we use Link tables in QV ? in QlikView

When do we use Link tables in QV ?

Anonymous — Tue, 13 Oct 2015 10:56:39 GMT

Hi,

Why and When do we use Link tables in QV data modeling . How is it different from Concatenation or joining the tables .

Thank you !

Re: When do we use Link tables in QV ?

oknotsen — Tue, 13 Oct 2015 11:04:55 GMT

You use a Link table when the facts do not share all the same dimensions.

Re: When do we use Link tables in QV ?

tresB — Tue, 13 Oct 2015 11:11:01 GMT

This blog :Concatenate vs Link Table should be helpful.

Re: When do we use Link tables in QV ?

gautik92 — Tue, 13 Oct 2015 11:16:51 GMT

if there are more than one fact table we create link table

Re: When do we use Link tables in QV ?

sujeetsingh — Tue, 13 Oct 2015 11:21:55 GMT

A table which links between two tables having relationship One to Many.

Re: When do we use Link tables in QV ?

oknotsen — Tue, 13 Oct 2015 11:25:28 GMT

That would mean you have a link table between almost every table.

I think you are mistaking "link table" for "link".

Re: When do we use Link tables in QV ?

Anonymous — Tue, 13 Oct 2015 11:26:50 GMT

Hi,

Please go through following links,

what is use of link tables ,how to use it

link table

What is Link Tables? What is the use?

thanks,

bunny

Re: When do we use Link tables in QV ?

Anonymous — Tue, 13 Oct 2015 11:32:14 GMT

Hi Mamtha,

In Data warehousing - Star schema usually have a single Fact in the centre and dimensions surrounding it but sometimes you have a situation where you have more than one Fact table.

In Qlikview,You come across a situation where you have to handle multiple Fact tables, which in turn create synthetic keys.

Link Table is a very useful way to resolve synthetic keys when multiple fact tables are present in the data model.

Link table is used, when the granularity of the facts tables are different and when they are joined to different dimensions.

To resolve these synthetic keys Link table:

You should always load Distinct records while creating Link table. Also if the Key field/composite field contains several individual fields then it is good to create Key field
Create a composite key. Using Auto number ( ) function like:
AutoNumber(YEAR&’|'&CUSTOMER_KEY&’|'&PRODUCT_KEY) As [%Key field]
Link table can connect to the original fact tables using this composite Key
Load all the common fields in one table called Link table
Drop these fields from the original tables.

Re: When do we use Link tables in QV ?

Anonymous — Wed, 14 Oct 2015 04:52:16 GMT

Thank you Neetha !