Data Analytics
Perfect channel to learn Data Analytics Learn SQL, Python, Alteryx, Tableau, Power BI and many more For Promotions: @coderfun @love_data
نمایش بیشتر📈 تحلیل کانال تلگرام Data Analytics
کانال Data Analytics (@sqlspecialist) در بخش زبانی انگلیسی بازیگری فعال است. در حال حاضر جامعه شامل 109 760 مشترک است و جایگاه 1 116 را در دسته فناوری و برنامهها و رتبه 2 331 را در منطقه الهند دارد.
📊 شاخصهای مخاطب و پویایی
از زمان ایجاد در невідомо، پروژه رشد سریعی داشته و 109 760 مشترک جذب کرده است.
بر اساس آخرین دادهها در تاریخ 26 ژوئن, 2026، کانال فعالیت پایداری دارد. در ۳۰ روز گذشته تغییر اعضا برابر 579 و در ۲۴ ساعت گذشته برابر 1 بوده و همچنان دسترسی گستردهای حفظ شده است.
- وضعیت تأیید: تأیید نشده
- نرخ تعامل (ER): میانگین تعامل مخاطب 2.58% است و در ۲۴ ساعت نخست پس از انتشار، محتوا معمولاً 0.93% واکنش نسبت به کل مشترکان کسب میکند.
- دسترسی پستها: هر پست به طور میانگین 2 827 بازدید دریافت میکند. در اولین روز معمولاً 1 016 بازدید جمعآوری میشود.
- واکنشها و تعامل: مخاطبان بهطور فعال حمایت میکنند؛ میانگین واکنش به هر پست 7 است.
- علایق موضوعی: محتوا بر موضوعات کلیدی مانند row, sql, analytic, analyst, visualization تمرکز دارد.
📝 توضیح و سیاست محتوایی
نویسنده این فضا را محل بیان دیدگاههای شخصی توصیف میکند:
“Perfect channel to learn Data Analytics
Learn SQL, Python, Alteryx, Tableau, Power BI and many more
For Promotions: @coderfun @love_data”
به لطف بهروزرسانیهای پرتکرار (آخرین داده در تاریخ 27 ژوئن, 2026)، کانال همواره بهروز و دارای دسترسی بالاست. تحلیلها نشان میدهد مخاطبان بهطور فعال با محتوا تعامل دارند و آن را به نقطه اثرگذاری مهم در دسته فناوری و برنامهها تبدیل کردهاند.
SELECT e1.name AS Employee, e2.name AS Manager
FROM employees e1
JOIN employees e2 ON e1.manager_id = e2.id;
In this example, the employees table is joined with itself to find the manager for each employee.
Tip: Explain that self joins are particularly useful for hierarchical data, such as organizational charts, and emphasize the importance of using table aliases (e.g., e1 and e2) to differentiate between the different instances of the same table.
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Hope it helps :)SELECT, INSERT, UPDATE, or DELETE statement. CTEs are defined using the WITH keyword and can improve the readability and organization of complex queries.
Example:
WITH EmployeeCTE AS (
SELECT department_id, AVG(salary) as avg_salary
FROM employees
GROUP BY department_id
)
SELECT e.name, e.salary, e.department_id, c.avg_salary
FROM employees e
JOIN EmployeeCTE c ON e.department_id = c.department_id
WHERE e.salary > c.avg_salary;
In this example, the CTE EmployeeCTE calculates the average salary per department, which is then used in the main query to find employees earning above the average salary in their department.
Tip: Explain that CTEs can be particularly useful for breaking down complex queries into more manageable parts, improving both readability and maintainability. They also allow for recursive queries, which can be useful in hierarchical data structures.
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Hope it helps :)SELECT name, salary, department_id,
ROW_NUMBER() OVER (PARTITION BY department_id ORDER BY salary DESC) as row_num
FROM employees;
In this example, ROW_NUMBER() assigns a unique rank to each row within each department, ordered by salary in descending order.
Tip: Highlight the usefulness of window functions for complex analytics and reporting tasks, where you need to perform calculations across rows while still returning individual rows. Explain other common window functions like RANK(), DENSE_RANK(), and NTILE().
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Hope it helps :)SELECT MAX(salary)
FROM employees
WHERE salary < (SELECT MAX(salary) FROM employees);
Tip: Explain that this approach can be useful when the LIMIT clause is not supported or if you want to demonstrate proficiency in using subqueries.
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Hope it helps :)SELECT DISTINCT salary
FROM employees
ORDER BY salary DESC
LIMIT n-1, 1;
Replace 'n' with the desired rank of the salary.
Tip: Emphasize the importance of using DISTINCT to handle cases where there are duplicate salaries, and ensure the ORDER BY clause is sorting the salaries in descending order to find the nth highest salary.
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Hope it helps :)SELECT, FROM, WHERE, and HAVING.
Types of Subqueries:
- Single-row subquery: Returns a single row and is used with operators like =, <, >.
- Multi-row subquery: Returns multiple rows and is used with operators like IN, ANY, ALL.
- Correlated subquery: A subquery that references columns from the outer query. It is evaluated once for each row processed by the outer query.
Examples:
- Single-row subquery:
SELECT name
FROM employees
WHERE department_id = (SELECT id FROM departments WHERE department_name = 'Sales');
- Multi-row subquery:
SELECT name
FROM employees
WHERE department_id IN (SELECT id FROM departments WHERE region = 'North');
- Correlated subquery:
SELECT e.name
FROM employees e
WHERE e.salary > (SELECT AVG(salary) FROM employees WHERE department_id = e.department_id);
Go though SQL Learning Series to refresh your basics
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Hope it helps :) CREATE TABLE customers (
customer_id INT PRIMARY KEY,
customer_name VARCHAR(100),
contact_number VARCHAR(15)
);
- Second Normal Form (2NF): Achieves 1NF and ensures that all non-key attributes are fully functionally dependent on the primary key. This means removing partial dependencies of any column on the primary key.
- Example: If a table has a composite key (e.g., order_id, product_id) and some columns depend only on part of that key, those columns should be moved to another table.
- Third Normal Form (3NF): Achieves 2NF and ensures that all the attributes are functionally dependent only on the primary key. This eliminates transitive dependencies.
- Example:
CREATE TABLE orders (
order_id INT PRIMARY KEY,
customer_id INT,
order_date DATE,
FOREIGN KEY (customer_id) REFERENCES customers(customer_id)
);
CREATE TABLE order_details (
order_id INT,
product_id INT,
quantity INT,
PRIMARY KEY (order_id, product_id),
FOREIGN KEY (order_id) REFERENCES orders(order_id)
);
- Boyce-Codd Normal Form (BCNF): A stricter version of 3NF where every determinant is a candidate key. This addresses situations where 3NF is not sufficient to eliminate all redundancies.
Tricky Question:
- How would you approach normalizing a table that contains repeating groups of data?
- This question tests the understanding of the concept of atomicity and the process of transforming a table into 1NF.
Example Answer:
- "If a table contains repeating groups, such as multiple phone numbers in one column separated by commas, I would first ensure that each piece of data is atomic. I would create a separate table for the repeating group and link it with a foreign key to the original table, thereby normalizing the data into 1NF."
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Hope it helps :)INNER JOIN and OUTER JOIN?
- INNER JOIN: Returns only the rows where there is a match in both tables.
- OUTER JOIN: Returns the matched rows as well as unmatched rows from one or both tables. There are three types of OUTER JOIN:
- LEFT OUTER JOIN (or LEFT JOIN): Returns all rows from the left table, and the matched rows from the right table. If no match is found, the result is NULL on the right side.
- RIGHT OUTER JOIN (or RIGHT JOIN): Returns all rows from the right table, and the matched rows from the left table. If no match is found, the result is NULL on the left side.
- FULL OUTER JOIN: Returns rows when there is a match in one of the tables. This means it returns all rows from the left table and the right table, filling in NULLs when there is no match.
Examples:
- INNER JOIN:
SELECT employees.name, departments.department_name
FROM employees
INNER JOIN departments ON employees.department_id = departments.id;
- LEFT JOIN:
SELECT employees.name, departments.department_name
FROM employees
LEFT JOIN departments ON employees.department_id = departments.id;
- RIGHT JOIN:
SELECT employees.name, departments.department_name
FROM employees
RIGHT JOIN departments ON employees.department_id = departments.id;
- FULL OUTER JOIN:
SELECT employees.name, departments.department_name
FROM employees
FULL OUTER JOIN departments ON employees.department_id = departments.id;
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Hope it helps :)CREATE, ALTER, DROP
- Example:
CREATE TABLE employees (
id INT PRIMARY KEY,
name VARCHAR(100),
position VARCHAR(50)
);
- DML (Data Manipulation Language): These commands are used to manipulate the data within the database.
- Examples: SELECT, INSERT, UPDATE, DELETE
- Example:
INSERT INTO employees (id, name, position) VALUES (1, 'John Doe', 'Manager');
- DCL (Data Control Language): These commands are used to control access to data within the database.
- Examples: GRANT, REVOKE
- Example:
GRANT SELECT ON employees TO user_name;
- TCL (Transaction Control Language): These commands are used to manage transactions in the database.
- Examples: COMMIT, ROLLBACK, SAVEPOINT
- Example:
BEGIN;
UPDATE employees SET position = 'Senior Manager' WHERE id = 1;
COMMIT;
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Hope it helps :)WITH cte_name AS (
SELECT column1, column2
FROM table_name
WHERE condition
)
SELECT column1, column2
FROM cte_name
WHERE another_condition;
Example Problem:
Find the top 3 highest-paid employees in each department.
Solution Using CTE:
WITH RankedSalaries AS (
SELECT
employee_id,
department_id,
salary,
ROW_NUMBER() OVER (PARTITION BY department_id ORDER BY salary DESC) AS rank
FROM employees
)
SELECT
employee_id,
department_id,
salary
FROM RankedSalaries
WHERE rank <= 3;
2. Window Functions:
Window functions perform calculations across a set of table rows related to the current row. They do not reduce the number of rows returned.
Common Window Functions:
- ROW_NUMBER(): Assigns a unique number to each row within the partition.
- RANK(): Assigns a rank to each row within the partition, with gaps in ranking for ties.
- DENSE_RANK(): Similar to RANK(), but without gaps.
- SUM(), AVG(), COUNT(), etc., over a partition.
Syntax:
SELECT column1,
column2,
window_function() OVER (PARTITION BY column1 ORDER BY column2) AS window_column
FROM table_name;
Example Problem:
Calculate the running total of sales for each salesperson.
Solution Using Window Function:
SELECT
salesperson_id,
sale_date,
amount,
SUM(amount) OVER (PARTITION BY salesperson_id ORDER BY sale_date) AS running_total
FROM sales;
Combining CTEs and Window Functions:
Example Problem:
Find the cumulative sales per department and the rank of each employee within their department based on their sales.
Solution:
WITH DepartmentSales AS (
SELECT
department_id,
employee_id,
SUM(sales_amount) AS total_sales
FROM sales
GROUP BY department_id, employee_id
),
RankedSales AS (
SELECT
department_id,
employee_id,
total_sales,
RANK() OVER (PARTITION BY department_id ORDER BY total_sales DESC) AS sales_rank
FROM DepartmentSales
)
SELECT
department_id,
employee_id,
total_sales,
sales_rank,
SUM(total_sales) OVER (PARTITION BY department_id ORDER BY sales_rank) AS cumulative_sales
FROM RankedSales;
For those of you who are new to this channel read SQL Basics before going through advanced concepts 😄
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Hope it helps :)Category) to the Columns shelf.
- Drag a measure (e.g., Sales) to the Rows shelf.
- Tableau automatically creates a bar chart.
2. Customizing the Bar Chart:
- Use the Color shelf to color bars by another dimension (e.g., Sub-Category).
- Adjust the Size shelf to change bar thickness.
- Add labels by dragging a measure to the Label shelf.
Line Charts
Line charts are ideal for showing trends over time.
1. Creating a Simple Line Chart:
- Drag a date field (e.g., Order Date) to the Columns shelf.
- Drag a measure (e.g., Sales) to the Rows shelf.
- Tableau creates a line chart automatically if the date field is continuous.
2. Customizing the Line Chart:
- Use the Color shelf to distinguish lines by category (e.g., Region).
- Add markers by checking the "Show Markers" option in the Marks card.
- Adjust the date granularity (e.g., year, quarter, month) by clicking on the date field in the Columns shelf and selecting the desired granularity.
Pie Charts
Pie charts show proportions and percentages of a whole.
1. Creating a Simple Pie Chart:
- Drag a dimension (e.g., Category) to the Columns shelf.
- Drag a measure (e.g., Sales) to the Rows shelf.
- Click on the Show Me panel and select the pie chart icon.
- Move Category to the Color shelf and Sales to the Angle shelf.
2. Customizing the Pie Chart:
- Add labels by dragging the dimension or measure to the Label shelf.
- Adjust the Size shelf to change the size of the pie chart.
- Use the Color shelf to adjust colors for better distinction.
Scatter Plots
Scatter plots show relationships between two measures.
1. Creating a Simple Scatter Plot:
- Drag one measure (e.g., Sales) to the Columns shelf.
- Drag another measure (e.g., Profit) to the Rows shelf.
- Tableau creates a scatter plot automatically.
2. Customizing the Scatter Plot:
- Add a dimension (e.g., Region) to the Color shelf to color code the points.
- Add another dimension to the Detail shelf to distinguish between data points.
- Adjust the Size shelf to change the size of the points.
Histograms
Histograms display the distribution of a single measure.
1. Creating a Histogram:
- Drag a measure (e.g., Sales) to the Columns shelf.
- Right-click the measure in the Columns shelf, select "Create Bins," and set the bin size.
- Drag the newly created bin field to the Columns shelf.
- Drag another measure (e.g., Number of Records) to the Rows shelf.
- Tableau creates a histogram.
2. Customizing the Histogram:
- Adjust bin size by editing the bin field.
- Use the Color shelf to color bins by another dimension.
- Add labels by dragging a measure to the Label shelf.
Geographic Maps
Geographic maps are used to visualize data geographically.
1. Creating a Simple Map:
- Drag a geographic dimension (e.g., State) to the Columns shelf.
- Drag a measure (e.g., Sales) to the Rows shelf.
- Tableau creates a map with filled areas.
2. Customizing the Map:
- Use the Color shelf to color the regions by the measure.
- Add labels by dragging the dimension or measure to the Label shelf.
- Adjust the map style and layers through the Map menu.
## Building Dashboards
Once you have individual visualizations, you can combine them into a dashboard.
1. Creating a Dashboard:
- Click the New Dashboard icon at the bottom of the Tableau workspace.
- Drag sheets from the Sheets pane to the dashboard workspace.
- Arrange and resize the visualizations as needed.
2. Adding Interactivity:
- Use filters, actions, and parameters to make your dashboard interactive.
- Add text boxes, images, and web content for additional context.
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Hope it helps :) [Profit] / [Sales]
2. Common Functions:
- String Functions: E.g., LEFT(), RIGHT(), MID(), CONCAT().
- Date Functions: E.g., DATEPART(), DATETRUNC(), DATEDIFF().
- Logical Functions: E.g., IF, THEN, ELSEIF, ELSE, END.
- Aggregate Functions: E.g., SUM(), AVG(), MIN(), MAX().
#### Level of Detail (LOD) Expressions
LOD expressions allow you to control the granularity of your calculations. They are useful for performing complex aggregations and analyses.
1. Types of LOD Expressions:
- Fixed: Calculates the value using the specified dimensions, ignoring other dimensions in the view.
{ FIXED [Region] : SUM([Sales]) }
- Include: Adds dimensions to the view’s level of detail.
{ INCLUDE [Category] : SUM([Sales]) }
- Exclude: Removes dimensions from the view’s level of detail.
{ EXCLUDE [Segment] : SUM([Sales]) }
#### Using Tableau Prep for Data Preparation
Tableau Prep is a tool specifically designed for data preparation, offering an intuitive interface to clean and shape your data.
1. Connecting to Data: Similar to Tableau Desktop, connect to your data sources.
2. Flows: Tableau Prep uses flows, which are sequences of steps (clean, shape, combine, etc.) that you apply to your data.
3. Cleaning Steps:
- Cleaning and Shaping: Perform tasks like renaming fields, changing data types, splitting fields, and pivoting data.
- Union and Join: Combine multiple tables using unions and joins.
- Aggregate and Group: Aggregate data to create summary statistics and group similar values.
4. Output: Once the data is prepared, you can output it to a file or publish it to Tableau Server/Tableau Online for use in Tableau Desktop.
#### Example of Data Preparation in Tableau Prep
1. Start Tableau Prep and connect to your data source (e.g., an Excel file).
2. Add Steps:
- Drag a "Clean Step" to rename fields, split columns, and fix data types.
- Drag a "Join Step" to combine multiple tables.
- Add a "Pivot Step" to reshape data if needed.
3. Output Data:
- Add an "Output Step" and choose the output location and format.
- Run the flow to generate the cleaned data.
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Hope it helps :)
اکنون در دسترس! پژوهش تلگرام ۲۰۲۵ — مهمترین بینشهای سال 
