Client Round Interview Experience: Tableau Developer at Goldman Sachs

Introduction:

• Interviewer: He started by introducing himself and his role within the team.
• Me: I introduced myself as Nagachandra Naidu, a Tableau Developer with 3 years of experience specializing in Tableau Development, Administration, and SQL.

Project Experience: I highlighted my work on three major projects:

1. GE Gas & Cash Escalation (Energy Domain): Extracted data from Snowflake to create interactive dashboards and reports using Tableau Desktop and SQL. As a developer, I identified regional ERP implementation gaps and resolved complex client issues by delivering insightful visual reports.
2. Capital One Bank (Banking Domain): Utilized Snowflake as the data warehouse and Tableau Desktop for visualization. I developed yearly, monthly, and weekly KPI reports, as well as customer status dashboards for business users.
3. Startek Finance (Finance Domain): Leveraged SAP HANA as the data source to create financial reports. I built yearly, monthly, and weekly budget and investment reports to assist stakeholders in strategic business decision-making.

Through these projects, I gained significant experience in project management, handling multiple clients simultaneously, and incorporating stakeholder feedback.

Technical Questions: SQL

1. What are Joins in SQL? Explain the different types.
2. Scenario: Table A has IDs (1, 2, 3, 4) and Table B has IDs (1, 2, 3). Provide the output for Inner, Left, Right, and Full Outer Joins.
3. Scenario: Table A has IDs (2, 3, 4, 6) and Table B has IDs (1, 2, 3, 5). What is the output for various Joins?
4. Logic Check: What is the output of the following query?
5. Explain Ranking functions in SQL (Row_Number, Rank, Dense_Rank) and their use cases.
6. What is the difference between the SQL order of writing (Syntax) and the SQL order of execution?
7. Explain the usage of WHERE, HAVING, and GROUP BY clauses.
8. What is the difference between UNION and UNION ALL? Provide specific use cases.

Technical Questions: Tableau

1. Explain Dimensions vs. Measures and Discrete vs. Continuous fields. What are their specific use cases?
2. What are the steps to connect SQL data sources to Tableau Desktop?
3. If I have a username and password in an encrypted format, can I use them to connect?
4. What is "Disaggregation" in Tableau, and when would you use it?
5. How do you access an external webpage from a dashboard when you have a URL?
6. Which Tableau components (Desktop, Server, Prep, Online) have you worked on?
7. Apart from Tableau, what other data visualization tools have you used?
8. Have you utilized any AI tools to assist in your development workflow?

My Questions to the Interviewer

1. What would be my primary roles and responsibilities during the first three months of joining the project?
2. What specific data sources are currently being utilized for this project?
3. Does the organization provide tutorials or resources for learning new technologies and tools required for the role?

Part 1: Professional Experience (Polished) 💼

Introduction:

"I am Nagachandra Naidu, a Tableau Developer with 3 years of experience in dashboard development, administration, and SQL. I have successfully delivered three major projects:

* GE (Energy Domain): Extracted data from Snowflake ❄️ to build interactive dashboards for the 'Gas and Cash Escalation' project. I identified regional ERP implementation gaps and transformed complex operational challenges into visual reports.

* Capital One (Banking Domain): Utilized Snowflake to develop comprehensive KPI reports (Yearly, Monthly, Weekly) and customer status trackers for executive business users.

* Startek (Finance Domain): Leveraged SAP HANA to create budget and investment reports, enabling data-driven decision-making across various financial timelines."

Part 2: SQL Technical Questions 📊

2) What are Joins in SQL?

Joins are used to combine rows from two or more tables based on a related column.

* Inner Join: Returns records with matching values in both tables.

* Left Join: Returns all records from the left table and matched records from the right.

* Right Join: Returns all records from the right table and matched records from the left.

* Full Join: Returns all records when there is a match in either table.

3) TableA (1,2,3,4) & TableB (1,2,3) Join Outputs:

* Inner: 1, 2, 3

* Left: 1, 2, 3, 4 (4 will have a NULL for TableB columns)

* Right: 1, 2, 3

* Full: 1, 2, 3, 4

4) TableA (2,3,4,6) & TableB (1,2,3,5) Output:

* Inner Join Result: 2, 3 (The only overlapping IDs).

5) Output of LEFT JOIN ON 1=1:

This creates a Cartesian Product (Cross Join). Since the condition 1=1 is always true, every row in Table A will be joined with every row in Table B. If Table A has 4 rows and Table B has 4 rows, you get 16 rows.

5b) Ranking Functions:

* ROW_NUMBER(): Unique number for every row.

* RANK(): Assigns same rank to ties but skips the next number (1, 2, 2, 4).

* DENSE_RANK(): Assigns same rank to ties without skipping (1, 2, 2, 3).

* Use Case: Identifying the top 5 highest-spending customers.

6) SQL Order of Writing vs. Execution:

* Writing: SELECT -> FROM -> WHERE -> GROUP BY -> HAVING -> ORDER BY.

* Execution: FROM -> WHERE -> GROUP BY -> HAVING -> SELECT -> ORDER BY.

7) WHERE vs. HAVING with GROUP BY:

* WHERE: Filters individual rows before grouping.

* HAVING: Filters aggregated groups after the GROUP BY is applied.

8) UNION vs. UNION ALL:

* UNION: Combines results and removes duplicates.

* UNION ALL: Combines results and keeps duplicates (faster performance).

Part 3: Tableau Technical Questions 🎨

1) Dimensions/Measures & Discrete/Continuous:

* Dimensions: Qualitative data (Names, Dates). They slice the data.

* Measures: Quantitative data (Sales, Profit). They are aggregated.

* Discrete (Blue): Creates headers.

* Continuous (Green): Creates an axis. 📈

2) Connecting SQL to Tableau:

Connect Pane -> To a Server -> Select Source (e.g., Snowflake) -> Enter Credentials -> Drag Tables to Canvas or use Custom SQL.

3) Using Encrypted Credentials:

If "excerpted" means encrypted, Tableau generally cannot use the encrypted string directly unless the database driver or an SSO (Single Sign-On) provider handles the decryption automatically.

4) Disaggregation:

By default, Tableau aggregates data. Disaggregating means showing every single row in the data source as a separate mark (Go to Analysis -> uncheck Aggregate Measures).

5) Accessing Webpages:

Use a URL Action. (Dashboard -> Actions -> Add Action -> Go to URL). This allows users to click a data point and open a related website.

6) Tableau Components:

Tableau Desktop (Development), Tableau Server/Online (Publishing/Admin), Tableau Prep (Data cleaning), and Tableau Reader.

7) Other Visualization Tools:

Power BI, QlikView, or Excel Dashboards.

8) AI Tools:

Tableau Pulse, Einstein Discovery, or ChatGPT/Gemini for SQL optimization.

Thanks,

Nagachandra Naidu