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Hi friends this is babu, plz help me this.
what is link table plz give with exaple friends.
plz help me friends.
Refer my post explain in details https://community.qlik.com/thread/110627
Vikas
also look this Re: what is use of link tables ,how to use it
(…) a junction table is a database table that contains common fields from two or more other database tables within the same database. It is on the many side of a one-to-many relationship with each of the other tables. Junction tables are known under many names, among them cross-reference table, bridge table, join table, map table, intersection table, linking table, many-to-many resolver, Link Table, pairing table, pivot table, transition table, or association table. (…).”
If you have two fact tables with some common fields you can concatenate both tables to create a link table.that link table will be like a fact table
Hi Babu,
Please go through below
There are two main strategies to modelling data in QlikView to handle multiple fact tables:
Positives:
Negatives:
How to construct Link Tables is a complex subject but relies upon traditional database linking table design techniques. It is easy to go wrong and produce linking tables that may seem to produce the correct results in the front-end but is excessively large, consuming memory and CPU resources.
In my experience, a poorly modelled QlikView data model is the most common culprit for causing poor performance.
I hope this quick, far from exhaustive, introduction to multi-fact modelling in QlikView proves of some help and sets you on the right course.
Link tables are generally used for linking the two table or the fact tables. With the use of link tables, it’s possible to keep the fact tables separated from each other. The advantage of this solution for choosing this method is to keep the data model a logical one. With the use of link tables, it’s possible to keep the fact tables separated from each other.
HI,
Link tables are what is often outside of QlikView in other BI-environments/DWH and in general called bridge tables. The purpose and the concept is the same. These tables maintain a many-to-many relationship between two or more tables. Link tables should be evaluated in respect to another approach that is CONCATENATED fact tables.
Excerpt from QlikView material about link tables:
When to use a Link Table
Let's look at when a link table might be required. Generally if you have a data model with multiple fact tables, that contain different measures and only minimal common dimensions, then you will likely need a link table. If your fact tables store their data at different levels of granularity i.e. a transactional table with daily data and a targets table with monthly data, then you will almost certainly need a link table. The purpose of the link table is to provide a seamless lik between all data in your application so that QlikView's (or Qlik Sense's) associative technology can be used to it's full potential. A badly implemented Link Table will have a significant and negative impact on the user's experience.
Henric Cronström in several of his blog posts and discussions on this forum recommend using concatenated fact tables in most cases instead of link tables. Link Tables are a necessity however when you need something called an alias dimension or role-playing dimension. Henric Cronström's paper on CANONICAL DATE shows in detail how a link table is created and maintained for this specific purpose
A special case of link table is the automatic creation of synthetic keys which QlikView does in the load script if it encounters two or more tables with more than one field (based on field-name) in common. Then it has to resort to this technique and create an intervening table it calls [$Syn <n> Table]. Also the use of INTERVAL MATCH will create a key and table like that which is in this case absolutely valid and necessary.
Regars
Gireesh
Hi,
Check for link table from slide number 30. Hope this will help you.