Dentsu World Services Data Analyst Interview Questions and Answers

Q1. Highlight the odd cells in excel
Ans. 
Use conditional formatting to highlight odd cells in Excel
• Select the range of cells you want to highlight

• Go to the 'Home' tab and click on 'Conditional Formatting'

• Choose 'New Rule' and select 'Use a formula to determine which cells to format'

• Enter the formula '=MOD(A1,2)=1' (assuming A1 is the top-left cell of your selected range)

• Choose the formatting style you want for the odd cells
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Q2. What are Joins in SQL, explain different joins and their outputs
Ans. 
Joins in SQL are used to combine rows from two or more tables based on a related column between them.
• Types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN

• INNER JOIN returns rows when there is at least one match in both tables

• LEFT JOIN returns all rows from the left table and the matched rows from the right table

• RIGHT JOIN returns all rows from the right table and the matched rows from the left table

• FU...read more
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Q3. Query to give running sum of salary
Ans. 
Use window function to calculate running sum of salary in SQL
• Use window function like SUM() with OVER() clause

• Partition the data by employee ID if needed

• Order the data by date or any other relevant column
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Well designed to test the aptitude competence of the candidate.

Q1. Explanations for the answers given to the aptitude questions.
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Q2. Questions from python.
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Q1. What are data structures in python,?
Ans. 
Data structures in Python are ways to store and organize data efficiently.
• Data structures in Python include lists, tuples, dictionaries, sets, and arrays.

• Lists are ordered, mutable, and can contain duplicate elements.

• Tuples are ordered, immutable, and can contain duplicate elements.

• Dictionaries are unordered, mutable, and store data in key-value pairs.

• Sets are unordered, mutable, and do not allow duplicate elements.

• Arr...read more
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Q2. Sql join questions
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The first round was a combination of MCQs and SQL Coding test. It consisted of 23 MCQs on SQL, 10 MCQs on Power BI and 5 SQL Coding questions.

Q1. Simple questions on SQL were asked.
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Q1. What is pivot table in Excel?
Ans. 
A pivot table in Excel is a data summarization tool that allows you to reorganize and summarize selected columns and rows of data.
• Pivot tables allow you to analyze and summarize large amounts of data in a spreadsheet.

• You can easily rearrange the layout of the data to view it from different perspectives.

• Pivot tables can perform functions like sum, average, count, and more on the data.

• They are useful for creating reports...read more
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Q2. What is 'Data Validation' in Excel?
Ans. 
Data Validation in Excel ensures that data entered in a cell meets certain criteria or conditions.
• Data Validation allows you to set rules for what can be entered in a cell, such as a range of values, a list of items, or a custom formula.

• Examples of Data Validation include setting a drop-down list of options for a cell, restricting input to a certain number range, or ensuring dates are entered in a specific format.

• Data ...read more
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Q3. What is the order of execution of an SQL query?
Ans. 
The order of execution of an SQL query involves multiple steps to retrieve data from a database.
• 1. Parsing: The SQL query is first parsed to check for syntax errors.

• 2. Optimization: The query optimizer creates an execution plan to determine the most efficient way to retrieve data.

• 3. Compilation: The optimized query is compiled into an executable form.

• 4. Execution: The compiled query is executed by the database engine t...read more
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Q4. What is the difference between Tree Map and Heatmap in Tableau?
Ans. 
Tree Map visualizes hierarchical data using nested rectangles, while Heatmap displays data values using color gradients.
• Tree Map displays data hierarchically with nested rectangles, where the size and color represent different measures.

• Heatmap visualizes data values using color gradients, with darker colors indicating higher values.

• Tree Map is useful for showing hierarchical data structures, while Heatmap is effective ...read more
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Q5. What is the difference between 'Extract Data' and 'Live Connection' in Tableau?
Ans. 
Extract Data saves a snapshot of data in Tableau workbook, while Live Connection directly connects to data source.
• Extract Data creates a static copy of data in Tableau workbook, while Live Connection directly queries data source in real-time.

• Extract Data is useful for working offline or with small datasets, while Live Connection is ideal for large datasets or when data is frequently updated.

• Extract Data can improve per...read more
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First round is gaming round with 13 levels
And the aptitude with science, technical and non technical questions

Q1. General questions were asked Tell me about yourself And then technical he round with puzzles and aptitude to solve
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Q2. Long term and short term goals
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Q3. Strength and weakness
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Q4. Puzzles and aptitude questions
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