Data Engineers
Free Data Engineering Ebooks & Courses
Show more๐ Analytical overview of Telegram channel Data Engineers
Channel Data Engineers (@sql_engineer) in the English language segment is an active participant. Currently, the community unites 10 345 subscribers, ranking 19 399 in the Education category and 40 316 in the India region.
๐ Audience metrics and dynamics
Since its creation on ะฝะตะฒัะดะพะผะพ, the project has demonstrated rapid growth, gathering an audience of 10 345 subscribers.
According to the latest data from 05 June, 2026, the channel demonstrates stable activity. Although there has been a change in the number of participants by 225 over the last 30 days and by 9 over the last 24 hours, overall reach remains high.
- Verification status: Not verified
- Engagement rate (ER): The average audience engagement rate is 11.49%. Within the first 24 hours after publication, content typically collects 2.44% reactions from the total number of subscribers.
- Post reach: On average, each post receives 1 188 views. Within the first day, a publication typically gains 252 views.
- Reactions and interaction: The audience actively supports content: the average number of reactions per post is 5.
- Thematic interests: Content is focused on key topics such as sql, learning, analytic, engineer, link:-.
๐ Description and content policy
The author describes the resource as a platform for expressing subjective opinions:
โFree Data Engineering Ebooks & Coursesโ
Thanks to the high frequency of updates (latest data received on 07 June, 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.
CREATE DATABASE db_name;
- USE db_name;
2. Tables
- Create Table: CREATE TABLE table_name (col1 datatype, col2 datatype);
- Drop Table: DROP TABLE table_name;
- Alter Table: ALTER TABLE table_name ADD column_name datatype;
3. Insert Data
- INSERT INTO table_name (col1, col2) VALUES (val1, val2);
4. Select Queries
- Basic Select: SELECT * FROM table_name;
- Select Specific Columns: SELECT col1, col2 FROM table_name;
- Select with Condition: SELECT * FROM table_name WHERE condition;
5. Update Data
- UPDATE table_name SET col1 = value1 WHERE condition;
6. Delete Data
- DELETE FROM table_name WHERE condition;
7. Joins
- Inner Join: SELECT * FROM table1 INNER JOIN table2 ON table1.col = table2.col;
- Left Join: SELECT * FROM table1 LEFT JOIN table2 ON table1.col = table2.col;
- Right Join: SELECT * FROM table1 RIGHT JOIN table2 ON table1.col = table2.col;
8. Aggregations
- Count: SELECT COUNT(*) FROM table_name;
- Sum: SELECT SUM(col) FROM table_name;
- Group By: SELECT col, COUNT(*) FROM table_name GROUP BY col;
9. Sorting & Limiting
- Order By: SELECT * FROM table_name ORDER BY col ASC|DESC;
- Limit Results: SELECT * FROM table_name LIMIT n;
10. Indexes
- Create Index: CREATE INDEX idx_name ON table_name (col);
- Drop Index: DROP INDEX idx_name;
11. Subqueries
- SELECT * FROM table_name WHERE col IN (SELECT col FROM other_table);
12. Views
- Create View: CREATE VIEW view_name AS SELECT * FROM table_name;
- Drop View: DROP VIEW view_name;
Here you can find SQL Interview Resources๐
https://t.me/DataSimplifier
Share with credits: https://t.me/sqlspecialist
Hope it helps :)SELECT test_group, AVG(purchase_amount) AS avg_purchase
FROM ab_test_results
GROUP BY test_group;
Run a t-test to check statistical significance (Python)
from scipy.stats import ttest_ind
t_stat, p_value = ttest_ind(group_A['conversion_rate'], group_B['conversion_rate'])
print(f"T-statistic: {t_stat}, P-value: {p_value}")
๐น P-value < 0.05 โ Statistically significant difference.
๐น P-value > 0.05 โ No strong evidence of difference.
2๏ธโฃ Forecasting & Trend Analysis
Forecasting predicts future trends based on historical data.
โ Time Series Analysis Techniques:
Moving Averages (smooth trends)
Exponential Smoothing (weights recent data more)
ARIMA Models (AutoRegressive Integrated Moving Average)
โ SQL for Moving Averages:
7-day moving average of sales
SELECT order_date,
sales,
AVG(sales) OVER (ORDER BY order_date ROWS BETWEEN 6 PRECEDING AND CURRENT ROW) AS moving_avg
FROM sales_data;
โ Python for Forecasting (Using Prophet)
from fbprophet import Prophet
model = Prophet()
model.fit(df)
future = model.make_future_dataframe(periods=30)
forecast = model.predict(future)
model.plot(forecast)
3๏ธโฃ KPI & Metrics Analysis
KPIs (Key Performance Indicators) measure business performance.
โ Common Business KPIs:
Revenue Growth Rate โ (Current Revenue - Previous Revenue) / Previous Revenue
Customer Retention Rate โ Customers at End / Customers at Start
Churn Rate โ % of customers lost over time
Net Promoter Score (NPS) โ Measures customer satisfaction
โ SQL for KPI Analysis:
Calculate Monthly Revenue Growth
SELECT month,
revenue,
LAG(revenue) OVER (ORDER BY month) AS prev_month_revenue,
(revenue - prev_month_revenue) / prev_month_revenue * 100 AS growth_rate
FROM revenue_data;
โ Python for KPI Dashboard (Using Matplotlib)
import matplotlib.pyplot as plt
plt.plot(df['month'], df['revenue_growth'], marker='o')
plt.title('Monthly Revenue Growth')
plt.xlabel('Month')
plt.ylabel('Growth Rate (%)')
plt.show()
4๏ธโฃ Real-Life Use Cases of Data-Driven Decisions
๐ E-commerce: Optimize pricing based on customer demand trends.
๐ Finance: Predict stock prices using time series forecasting.
๐ Marketing: Improve email campaign conversion rates with A/B testing.
๐ Healthcare: Identify disease patterns using predictive analytics.
Mini Task for You: Write an SQL query to calculate the customer churn rate for a subscription-based company.
Data Analyst Roadmap: ๐
https://t.me/sqlspecialist/1159
Like this post if you want me to continue covering all the topics! โค๏ธ
Share with credits: https://t.me/sqlspecialist
Hope it helps :)
Available now! Telegram Research 2025 โ the year's key insights 
