Qlikview Interview Questions & Material

1). Explain QlikView Resident Load?

Ans: In qlikview ,resident load can be used to load data from a previously loaded table.

2). What is Incremental load?

Ans: Incremental load is one of the toughest part in qlikview .It is used to load new or changed data.it loads the old data from qvd files and new data from databases

3). Difference between QVD and QVW?

Ans:  QVW: A qlikview file saved in binary format having the default expression QVW. Also called Qlik View file.qvw file contains tables, charts script etc.
QVD: a native Qlik View file format, A QVD file contains one data table, no layout and no security. It is basically a binary CSV file optimized for fast loading.

4). What is Interval Match?

Ans: The interval match prefix to load or select statement is used for linking discrete numeric values to one or more numeric intervals Ex. Interval match(field)(load statement/select statement)

5). What is Container ?

Ans:  A container object can be used to hold multiple charts.  You can use a container object to put multiple charts in the same box. All charts will appear in the same window but only one chart will appear active at a given time. You can click the chart title to switch or toggle between charts. A word of advice: Use containers with caution. They form linked objects and might affect the properties of all linked objects.

6). What is a synthetic key?

Ans: It is a field that contains all possible combinations of common fields among tables.

7). What are the layers in QV?

Ans: The layers are set on the sheet object properties layout where bottom, top, normal corresponding to the numbers -1,0,and 1 choose custom to enter value of your choice valid layer numbers are -128 to 127.

8).How are NULLS implemented in QlikView?

Ans: The way in which QlikView's associative engine works means Nulls don't really exist in the data it holds, a Null is simply an absence of a data item. For example if a field value is missing we can’t make selection on empty list box. We can replace these null values with our required values(NA,0, etc) .

9). What is QVX?

Ans: QVX Stands Qlikview Data Exchange .Is used to create your own connector that can connect to qlikview files. Used when you are not using OLEDB/ODBC

10). What is Apply Map (Mapping Tables)?

Ans: Sometimes you need to add an extra field to a table to use a combination of fields from different tables, or you want to add a field to clean up the data structure. 

Qlik- View has an effective way to add single fields to a table called mapping tables.  

syntax — mapping ( load statement | select statement )applymap( ‘mapname’, expr, [ , defaultexpr ] )

11). what is Set and let in QlikView and difference between it?

Ans:  SET or a LET statement is often used to define the variable. The SET statement is used when you want a variableto hold the string or numeric value that is to the right of the Equal (=) sign.The LET statement is used when you need to evaluate what is to the right of the Equal sign

Example:

set myVar=5*2   the result is “5*2″

Let myVar=5*2   the result is “10″

12)Have you used macros in your application? What you have used?

Ans: we can use macros for various things 
a)we can call the macro to reload the application 
b)we can call the macro to create objects

13). What is Central Link Table?

Ans: In the event of multiple fact tables QlikView In-Memory Technology allows us to create a central link table that only contains the existing data combinations. Instead of Joining the tables the event dimensions can be merged (CONCATENATED) in to one central Link table. This link table can then be linked back to the event measures one side and the dimension tables on the other.

14). Difference between keep and joins ?

Ans:  Left Keep and Left join gives the same output. The only difference is that Left Keep keeps the Table separate in Data Model, whereas Left join merges the Tables that are joined.

15). Why sorting not possible while loading QVD?

Ans: Sorting (ORDER BY) is only possible with Resident (already in memory) files. Sorting  is not possible when reading from files

16). Explain Qlikview architechture?

Ans: QlikView is the world’s first associative, in-memory business intelligence platform. QlikView manages associations among data sets at the engine level, not the application level, by storing individual tables in its in-memory associative engine. QlikView is the most flexible Business Intelligence platform for turning data into knowledge.Effective decision-making is based on having the right information available and easy accessible. 

17). What is the difference between Subset and Information Density?

Ans: Information Density: is the number of records that have values (i.e. not NULL) in this field as compared to the total number of records in the table.SubSet Ratio:Subset ratio, which shows the percentage of all distinct values for a field in the table compared to all the distinct values for that field in the entire data model.

18). What is Snowflaking Schema ?

Ans: Snowflaking is a form of dimensional modeling,  dimensions are stored in multiple relational dimension tables.  A snowflake schema is a variation of the star schema. Snowflaking is used to improve the performance of specific queries.  The schema is diagramed with each fact surrounded by its associated dimensions as in a star schema, and those dimensions are further related to other dimensions, branching out into a snowflake pattern.

19). What is cluster?

Ans: for load balancing we have to install it with separate license when availability small business server only we can install Clusters. It will give high availability to the application( Zero Down time)

20). How do you bring data into QV? Explain the script?

Ans: We can load data from ODBC, OLEDB,SAP connectors by connect, select statements and also we can load flat files like excel, word, xml etc by using Table files syntax will be Directory: Load tables, from Ramsample.txt;
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