Qlikview Mapping

What is QlikView Mapping?

QlikView Mapping is incidentally creating a table (mapping table) utilizing information or field values from prior tables from various models and sources. The mapping tables are put away in QlikView's memory just till the content is implemented and from that point forward, it is naturally removed. Mapping makes a table with arranged information fields and values whose script can be availed in various manners via statements or as functions (Rename Field, MapSubstring(), ApplyMap(), Map… Using and so forth) You can supplant field names or esteems during content execution utilizing mapping.

A Mapping table is made to plan the column values among two tables. It is also known as a Lookup table, that is simply used to search for a value from some other table. There are numerous functions accessible in this Mapping strategy to deal with the database table mapping. Mapping tables or Mapping load fills in as a choice to Join statements in the data set. The lookup value and the mapping value are the two columns in the mapping table. Mapping Tables are transitory tables as they are naturally taken out from the information model before the end of the implementation of the content. 

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QlikView Mapping Load Statement

The Mapping Load statement is utilized to stack fields and values into a newly made mapping table in QlikView. 

Syntax

Mapping(loadstatement | selectstatement)

The term Mapping is utilized as a prefix to LOAD or SELECT proclamations directing the framework to save the stacked fields in the mapping table. A mapping table includes two columns of which, the first includes values for examination (as a kind of reference point) and second includes the outcome or wanted values dependent on the correlation. For example, when country codes are used as the reference section and second resultant column is  nation names. The nation codes will be supplanted by the comparing nation names upon content implementation.

Example for mapping load in QlikView,

// Load mapping table of country codes:

MapCountry:

mapping LOAD * 

Inline [

CountryCode, Country

Sw, Sweden

Ind, India

Chn, China

Ity, Italy,

Cnd, Canada

Dk, Denmark

No, Norway

];

Along these lines, this will stack a mapping table called MapCountry which has two columns, Country and CountryCode. The elements of the given mapping tables can be utilized in turn by planning statements and other operations like ApplyMap. 

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QlikView ApplyMap Function

The QlikView ApplyMap() function brings content from a current mapping table. It also maps the outcome of an expression to a current field from the mapping table. 

Syntax

ApplyMap('map_name', expression [ , default_mapping ] )

Here, map_name is the name given to the pre-existing mapping table. The expression is the field whose outcome must be mapped to a mapping table field. default_mapping is the value, whenever referenced will be returned if there is no match of the field esteems from the current mapping table. The worth is returned all things considered in the output table, if not referenced.

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Example of Qlikview ApplyMap Function

Allow us to improve comprehension of this by the assistance of an example. Consider the one with a similar nation code example as we utilized in the mapping load area.

// Load list of store managers, mapping country code to country

StoreManagers:

LOAD *, 

ApplyMap('MapCountry', CountryCode,'Others') As Country

Inline [

CountryCode, StoreManager

Sw, John Dalton

Cnd, Mary Robins

Ity, Andrea Russo 

Arg, Harry Gibson 

Dk, William Gilbert

Ind, Indrani Sen

No, Daniel Larsen

Rom, Emilia Mark];

// We don't need the CountryCode anymore

Drop Field 'CountryCode';

The resultant table will look as given below.

From this table, the name of the nation relating to the nation code composed next to the store supervisor name is mapped into the last table utilizing an applymap function. Likewise, those nations (like Arg and Rom) for which there were no reference country names in the table "MapCountry" are composed as "Others". 

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Benefit of utilizing Mapping table and ApplyMap Function: 

• Aids in dodging joins in QlikView. 
• Aids in diminishing tables from the data model to simplify it, productive and justifiable. 
• Mapping Table is only there during load. 
• Missing rows can be dealt with by its third parameter  consequently aids in taking care of the null qualities and utilized in information integrity in ApplyMap Function.
• It disregards the duplicate rows in the table. 
• We can utilize composite keys as a critical column in the table. 
• We can make different maps from a similar table. 
• It saves processor time and memory. 
• It cleans the information by eliminating the information disparities.

QlikView Architecture

QlikView is developed with a totally different way to deal with information disclosure than other conventional platforms. It doesn't initially assemble an inquiry and afterward bring the outcome dependent on the query. It structures relationships between various data objects when it is stacked and prompts the client to investigate the information in any capacity. The information drill down ways can occur toward any path as long as the information is accessible and related. A client can assume a part in making the connection between information components utilizing information modeling approach accessible in QlikView.

QlikView's architecture comprises a front end to picturize the prepared information and a back end to give the security and distribution component for QlikView client records. The image given above portrays the inside working of QlikView. 

Front End

Front end in QlikView can be defined as a browser oriented access point for reviewing the QlikView archives. It includes the QlikView Server, that is fundamentally utilized by the Business clients to get to already made Business Intelligence reports via a web or intranet URL. Business clients investigate and interface with information utilizing this front end and determine decisions about the information. They team up with different clients on a given arrangement of reports by sharing bits of knowledge and investigating information together, continuously or offline. These client archives are in the configuration .qvw, which can be put away in the windows OS as an independent record. The QlikView server in it deals with the customer server correspondence between the client and QlikView backend framework.

Back End 

The QlikView backend comprises QlikView publisher and QlikView desktop. The QlikView desktop can be considered as a wizard-driven Windows environ, that has the highlights to stack and change information from its source. Its simplified element is utilized to make the GUI format of the reports which gets noticeable in the frontend. The record types that are made by the QlikView desktop are put away with an extension of .qvw. These are the documents which are given to the QlikView server in the front end, that serves the clients with other records. .qvw documents can be adjusted to store the information only records, called as .qvd records. They are records that include just the information and not the GUI parts. The QlikView publisher is utilized as a circulation service to convey the .qvw reports among different QlikView servers and clients. It manages the approval and access advantages. It does the immediate stacking of information from the data sources by utilizing the association strings characterized in the .qvw records.

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Highlights of QlikView planning 

Some significant highlights of QlikView planning are: 

• It is like the query function where a field esteem is utilized as a source of reference to another field existing in the mapping table and returns a coordinating outcome. 
• A mapping table is always made by Mapping Load or Mapping Select prior to applying a Map work. 
• A mapping table stays briefly in the memory of QlikView till the next time content implementation is finished. It is exited once a content is executed. 
• The transitory mapping table doesn't influence the fundamental information tables put away in-memory of QlikView. 
• Any mapping table can be reviewed and reutilised in a content however many occasions as a client needs. 
• The principal field is known as a key and the subsequent field or column is alluded to as mapped value ALWAYS. 
• All the planning necessities can be done in a solitary script.

Conclusion

The blog dealt with QlikView mapping with QlikView ApplyMap() and mapping load. We get to know more about mapping, how to make mapping tables utilizing the Mapping Select statements or Mapping Load lastly and how to utilize mapping via the ApplyMap() work.

Other Related Articles:

• Synthetic keys in QlikView
• Incremental Load in QlikView
• QlikView Interview Questions