Top Tableau Scenario-Based Interview Questions Set -3 (1- 10)

 

1. How would you combine historical and current data?
   Use UNION to append both datasets having same columns.
   Example SQL:

   SELECT * FROM Sales_History
   UNION ALL
   SELECT * FROM Sales_Current
   

   In Tableau, drag one table below another to create union.

2. How would you union monthly files automatically?
   Use Wildcard Union in Tableau for files with similar structure.
   Example:

   Sales_Jan.csv
   Sales_Feb.csv
   Sales_Mar.csv
   

   Use:

   Sales_*.csv
   

   Tableau automatically combines all matching files.

3. How would you handle null values?
   Use IFNULL() or ZN() to replace nulls.
   Example:

   IFNULL([Profit],0)
   

   or

   ZN([Sales])
   

   to convert NULL into 0.

4. How would you replace missing dates in a trend chart?
   Convert date to continuous and enable “Show Missing Values.”
   Example:

   MONTH([Order Date])
   

   Then right-click axis → Show Missing Values.

5. How would you create a complete date scaffold?
   Create a calendar table containing all dates and join with fact table.
   Example SQL:

   SELECT Calendar.Date, Sales.Amount
   FROM Calendar
   LEFT JOIN Sales
   ON Calendar.Date = Sales.OrderDate
   

   This ensures all dates appear even without transactions.

6. How would you show data when no transactions exist?
   Use LEFT JOIN with dimension/scaffold table.
   Example:

   SELECT C.CustomerName, IFNULL(SUM(S.Amount),0)
   FROM Customers C
   LEFT JOIN Sales S
   ON C.CustomerID = S.CustomerID
   GROUP BY C.CustomerName
   

   Customers with no sales still appear.

7. How would you use relationship vs join?
   Use Relationships for logical layer and Joins for physical merge.
   Example:
   • Relationship keeps tables separate until query time.
   • Join physically combines rows immediately using Inner/Left Join.

8. How would you optimize a slow dashboard?
   Reduce marks, avoid unnecessary quick filters, and simplify calculations.
   Example:

   IF SUM([Sales]) > 1000 THEN "High" END
   

   Replace complex nested calculations with simpler logic.

9. How would you improve dashboard load time?
   Use extracts instead of live connection and aggregate data.
   Example:

   SUM([Sales])
   

   at Month level instead of transaction level reduces records processed.

10. How would you improve filter performance?
    Use Context Filters so Tableau processes smaller datasets first.
    Example:

• Add Region filter to Context.
• State filter now works only on selected Region data.

11. How would you optimize heavy LODs?
    Push calculations to database or simplify FIXED calculations.
    Example:

{ FIXED [Customer ID] : SUM([Sales]) }

Instead of multiple nested LODs, pre-aggregate data in SQL/ETL.

Bhagavad Gita Wisdom #shorts

https://www.youtube.com/playlist?list=PLQM-BpTd9ZSumxwKgJjuJjlx2OcP_W516 

Top Tableau Scenario-Based Interview Questions Set -2 (1- 10)

1. How would you create a dynamic title?
   Create a calculated field or directly insert parameter/filter values into the title.
   Example Title:

   Sales Report for YEAR[Order Date])
   

   Or use:

   "Sales for " + [Region]
   

2. How would you show KPI cards with arrows?
   Create a KPI calculation comparing current vs previous period.
   Example:

   IF SUM([Sales]) > LOOKUP(SUM([Sales]),-1)
   THEN "▲"
   ELSE "▼"
   END
   

   Use shapes/colors: Green for increase, Red for decrease.

3. How would you build dependent filters?
   Add Country filter first, then State filter and select “Only Relevant Values.”
   Example: Selecting India shows Karnataka, Delhi, etc., while USA shows Texas, California.
4. How would you implement cascading filters?
   Use parent-child filters where child values depend on parent selection.
   Example:
   Country → State → City
   Selecting “India” filters only Indian states and cities.

5. How would you create a customer search box?
   Create a parameter for user input and use a calculated field:

   CONTAINS(LOWER([Customer Name]), LOWER([Search Parameter]))
   

   Place calculation on Filters and keep TRUE.

6. How would you drill down Region → State → City?
   Create hierarchy by dragging State under Region and City under State.
   Users can click “+” icon to expand from Region → State → City interactively.
7. How would you create a reset filters button?
   Create a duplicate dashboard with default filters and use navigation button.
   Clicking Reset redirects users to original dashboard with default filter values.

8. How would you blend sales and target data?
   Use Sales as primary source and Target as secondary source linked by Region/Date.
   Example Calculation:

   SUM([Sales]) - SUM([Target])
   

   to show variance.

9. How would you join 3 tables with different granularity?
   Aggregate lower-granularity tables before joining.
   Example:
   Sales at Order level and Budget at Monthly level → aggregate Sales:

   SUM([Sales])
   

   by Month before joining.

10. How would you handle duplicate rows after joins?
    Use FIXED LOD or aggregation to avoid duplicated measures.
    Example:

    { FIXED [Order ID] : SUM([Sales]) }

        This ensures Sales is counted once per Order ID.

Bhagavad Gita Wisdom #shorts

https://www.youtube.com/playlist?list=PLQM-BpTd9ZSumxwKgJjuJjlx2OcP_W516