Data Analyst Interview Resources
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Channel Data Analyst Interview Resources (@dataanalystinterview) in the English language segment is an active participant. Currently, the community unites 52 614 subscribers, ranking 3 245 in the Education category and 6 767 in the India region.
📊 Audience metrics and dynamics
Since its creation on невідомо, the project has demonstrated rapid growth, gathering an audience of 52 614 subscribers.
According to the latest data from 27 August, 2026, the channel demonstrates stable activity. Although there has been a change in the number of participants by 60 over the last 30 days and by -8 over the last 24 hours, overall reach remains high.
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- Engagement rate (ER): The average audience engagement rate is 1.93%. Within the first 24 hours after publication, content typically collects 0.83% reactions from the total number of subscribers.
- Post reach: On average, each post receives 1 018 views. Within the first day, a publication typically gains 438 views.
- Reactions and interaction: The audience actively supports content: the average number of reactions per post is 2.
- Thematic interests: Content is focused on key topics such as sql, row, |--, dataset, visualization.
📝 Description and content policy
The author describes the resource as a platform for expressing subjective opinions:
“Join our telegram channel to learn how data analysis can reveal fascinating patterns, trends, and stories hidden within the numbers! 📊
For ads & suggestions: @love_data”
Thanks to the high frequency of updates (latest data received on 28 August, 2026), the channel maintains relevance and a high level of publication reach. Analytics show that the audience actively interacts with content, making it an important point of influence in the Education category.
CALCULATE(SUM(Sales[Amount]), Region = "West")
2️⃣ What is ALL() function in DAX?
Removes filters — useful for calculating totals regardless of filters.
3️⃣ How does FILTER() differ from CALCULATE()?
FILTER returns a table; CALCULATE modifies context using that table.
4️⃣ Difference between SUMX and SUM?
SUMX iterates over rows, applying an expression; SUM just totals a column.
5️⃣ Explain STAR vs SNOWFLAKE Schema
- Star: denormalized, simple
- Snowflake: normalized, complex relationships
6️⃣ What is a Composite Model?
Allows combining Import + DirectQuery sources in one report.
7️⃣ What are Virtual Tables in DAX?
Tables created in memory during calculation — not physical.
8️⃣ What is the difference between USERNAME() and USERPRINCIPALNAME()?
Used for dynamic RLS.
- USERNAME(): Local machine login
- USERPRINCIPALNAME(): Cloud identity (email)
9️⃣ Explain Time Intelligence Functions
Examples:
- TOTALYTD(), DATESINPERIOD(), SAMEPERIODLASTYEAR()
Used for date-based calculations.
🔟 Common DAX Optimization Tips
- Avoid complex nested functions
- Use variables (VAR)
- Reduce row context with calculated columns
1️⃣1️⃣ What is Incremental Refresh?
Only refreshes new/changed data – improves performance in large datasets.
1️⃣2️⃣ What are Parameters in Power BI?
User-defined inputs to make reports dynamic and reusable.
1️⃣3️⃣ What is a Dataflow?
Reusable ETL layer in Power BI Service using Power Query Online.
1️⃣4️⃣ Difference Between Live Connection vs DirectQuery vs Import
- Import: Fast, offline
- DirectQuery: Real-time, slower
- Live Connection: Full model lives on SSAS
1️⃣5️⃣ Advanced Visuals Use Cases
- Decomposition Tree for root cause analysis
- KPI Cards for performance metrics
- Paginated Reports for printable tables
👍 Tap for more!WHERE filters rows before grouping (used with SELECT, UPDATE).
⦁ HAVING filters groups after aggregation (used with GROUP BY), e.g., filtering aggregated results like sums or counts.
5. Write a SQL query to find the second highest salary in a table.
Using a subquery:
SELECT MAX(salary) FROM employees
WHERE salary < (SELECT MAX(salary) FROM employees);
Or using DENSE_RANK():
SELECT salary FROM (
SELECT salary, DENSE_RANK() OVER (ORDER BY salary DESC) as rnk
FROM employees) t
WHERE rnk = 2;
6. What is a JOIN? Explain different types of JOINs.
A JOIN combines rows from two or more tables based on a related column:
⦁ INNER JOIN: returns matching rows from both tables.
⦁ LEFT JOIN (LEFT OUTER JOIN): all rows from the left table, matched rows from right.
⦁ RIGHT JOIN (RIGHT OUTER JOIN): all rows from right table, matched rows from left.
⦁ FULL JOIN (FULL OUTER JOIN): all rows when there’s a match in either table.
⦁ CROSS JOIN: Cartesian product of both tables.
7. How do you optimize slow-performing SQL queries?
⦁ Use indexes appropriately to speed up lookups.
⦁ Avoid SELECT *; only select necessary columns.
⦁ Use joins carefully; filter early with WHERE clauses.
⦁ Analyze execution plans to identify bottlenecks.
⦁ Avoid unnecessary subqueries; use EXISTS or JOINs.
⦁ Limit result sets with pagination if dealing with large datasets.
8. What is a primary key? What is a foreign key?
⦁ Primary Key: A unique identifier for records in a table; it cannot be NULL.
⦁ Foreign Key: A field that creates a link between two tables by referring to the primary key in another table, enforcing referential integrity.
9. What are indexes? Explain clustered and non-clustered indexes.
⦁ Indexes speed up data retrieval by providing quick lookups.
⦁ Clustered Index: Sorts and stores the actual data rows in the table based on the key; a table can have only one clustered index.
⦁ Non-Clustered Index: Creates a separate structure that points to the data rows; tables can have multiple non-clustered indexes.
10. Write a SQL query to fetch the top 5 records from a table.
In SQL Server and PostgreSQL:
SELECT * FROM table_name
ORDER BY some_column DESC
LIMIT 5;
In SQL Server (older syntax):
SELECT TOP 5 * FROM table_name
ORDER BY some_column DESC;
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