QlikView Interview Questions and Answers

Synthetic Keys: when two or more tables have two or more fields in common is called synthetic key. Below are the ways to remove synthetic keys

• Join
• Alias
• Concatenated key
• Link table
• Qualify

Circular reference/loops: There are more than one path of association between two fields below are the ways to remove.

• Alias
• Qualify
• Link table (join)
• Concatenation

Join: it joins the loaded table with an existing named table or last previously created logical table.

Join are of 4 types

• Inner Join
• Outer Join
• Left Join
• Right Join

Concatenation: If the two tables have different fields concatenation of the two tables can be forced with concatenation prefix.

No Concatenation: if the two tables have same fields also No Concatenate treats as separate internal tables

The SQL select statement is used to identify fields and tables to load from the current database connection.

The load statement loads fields from a typed ASCII file from data defined in the script from previously loaded input table, from previously loaded field. From the result of the following select statements or by generating automatically

Star Schema: In a star schema, the fact table will be at center and in connected to dimensional tables. The tables are completely in De normalized Structure. SQL queries performance in good as there are less number of joins involved. Data redundancy is high and occupies more disk spaces.

Snowflake Schema: is an extension of star schema where the dimension tables are further connected to one or more dimensions. The tables are partially de normalized in structure. The performance of SQL queries is little bit less compared to star schema as more no. of joins are involved. Data redundancy is low and occupies less disk space compared to star schema.

Fact Constellation Schema is describes a logical database structure of Data Warehouse or Data Mart. Fact Constellation Schema can design with collection of De Normalized Fact, Shared and conformed dimensional tables. Fact Constellation Schema is an extended Decomposed Star Schema.

To connect a QlikView server (QVS) each client needs a CAL (client access license) The CAL’s are purchased with QlikView Server and tied to the server serial number. A CAL is never transformed to the client but a client uses the CAL when connecting to the server.

Cal Types:

• Named User CAL: Named CAL can access all the documents
• Document CAL: Document CAL can access particular document
• Session CAL: A session allows any user identified or anonymous/unidentified on one QV client to access many QV documents as may reside on the server
• Usage CAL: allows any user to access only one QV document residing on the server

QV Server: is a program that is installed in a physical server (computer) with number of CAL’s these allow user to access QV files on the server. QVS controls the people who can access the documents on server using client access license (CAL).

QV Publisher: is a program which allows you to maintain centralized control of all your QV files and to schedule when and how they reloaded and distributed. You can automatically reload files and distribute them to web access points or by email or intranet. You can do data reduction also.

Cross table is common type of table featuring a matrix of values between two orthogonal lists of header data. To turn cross table into straight table use cross table prefix

Ex. Cross table (attribute field name, data field name [ , n ] ) ( load statement | select statement )

Set: this command assigns the variable the text to the right of equal sign.

Let: assigns the variable whereas Let command evaluates expression.

Ex. Set Variable name = String

Let variable name= operation

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;

flat files, excel, QVD’s etc…

Trellis: open the Trellis setting in chart properties, you can create an array of charts based on first dimension any type of bitmap chart can be made into trellis display.

1. We can enable trellis chart
2. Enable secondary Trellis Dimension
3. We can give no of columns to display in chart

It is only available when the mini chart option has been selected in the expression page of straight table properties dialog. Opens a dialog for setting the properties of the mini chart, we can set mode type instead of values in table mode are: spark lines, line with dots, dots, bars or whiskers we can set color also

List box, gauge chart

We can use macros for various things

1. We can call the macro to reload the application
2. We can call the macro to create objects

The layer 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

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.

Cluster: 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)

Bar Chart: Comparison of similar measurements

• Actual vs budget- money to money. Quarter to Quarter
• Time to Time
• Top N- categorized values (sales reps, customers etc…)

Avoid: comparisons with different units ($ and Qty)

Line chart: measurements to follow its moments or comparisons among items

• Performance trends- amount of moment over time
• Two Dimension comparisons- Annual comparisons over month

Combo Charts: Comparisons for multi measurements

• Two measurements- currency amount and quantity or amount percentage
• Two axis- different measurements on left and right axis
• Two or more axis: split axis horizontally

Radar chart: Comparisons of high level groups

• One or two measurements- sales and profit
• Avoid- a dimension with many values

Gauge chart: Ratio of measurements

• Percentages- margin, quota achieved, year-tot
• Date vs last YTD.

Avoid: actual amounts

Mekko chart: Data using variable width bars

• 3D measurement chart- Amount, Quantity and no. of customers
• Market analysis.

Scatter Chart: Measurement acts as dimensions (3D Chart)

• 3D measurement chart- Amount, Quantity and no. of customers
• Map chart- see sales on Geographical map

Grid Chart: 2 or 3 Dimensions with a measurement

• Multi-cross dimensional measurements
• amounts over- region and product and over time

Pie Chart: Visual Distribution measurements

• what contributes how to the whole- regional sales
• yes/no analysis

Funnel chart: Dimension that contain an expiration time line

• how much is the most aging element
• Sales opportunities
• Product Inventory Expressions

Block chart: Distribution measurements within multi dimensions

• what contributes how to whole and within each segments
• Sales contribution per country

Straight Table: one dimension with multiple measurements

• KPI overview- cyclic group dimensions with sales Qty, margin
• Sort in any no of columns (no grouping)

Pivot table: multi dimensions with one or more measurements

• Grouping of dimensions
• Dimensions across the table and displaying sub totals

First sorted value: It returns the first value of expression sorted by corresponding Sort weight. Sort weight should be a numeric value.

Uses:

1. Get the latest field value based on time stamp
2. Bigger customer for each product category
3. Find the min/max values and extract related field
4. Compare highest and second value
5. Look up min/max value within range

Extended Interval Match function(): It is used for slowly changing dimensions

Relative Path: If we select Relative path, then we the work path is defined by directory statement. If it is not selected, the path of the QVW defines work directory. The work directory can be found in the system variable QVWORKROOT which should not be changed manually.