Data Engineers
Free Data Engineering Ebooks & Courses
Mostrar más📈 Análisis del canal de Telegram Data Engineers
El canal Data Engineers (@sql_engineer) en el segmento lingüístico de Inglés es un actor destacado. Actualmente la comunidad reúne a 10 900 suscriptores, ocupando la posición 17 980 en la categoría Educación y el puesto 35 495 en la región India.
📊 Métricas de audiencia y dinámica
Desde su creación el невідомо, el proyecto ha mostrado un crecimiento acelerado, reuniendo a 10 900 suscriptores.
Según los últimos datos del 28 agosto, 2026, el canal mantiene una actividad estable. En los últimos 30 días la variación de miembros fue de 278, y en las últimas 24 horas de 1, conservando un alto alcance.
- Estado de verificación: No verificado
- Tasa de interacción (ER): El promedio de interacción de la audiencia es 11.27%. Durante las primeras 24 horas tras publicar, el contenido suele obtener 3.15% de reacciones respecto al total de suscriptores.
- Alcance de las publicaciones: Cada publicación recibe en promedio 1 227 visualizaciones. En el primer día suele acumular 343 visualizaciones.
- Reacciones e interacción: La audiencia responde de forma activa: el promedio de reacciones por publicación es 7.
- Intereses temáticos: El contenido se centra en temas clave como sql, learning, analytic, engineer, link:-.
📝 Descripción y política de contenido
El autor describe el recurso como un espacio para expresar opiniones subjetivas:
“Free Data Engineering Ebooks & Courses”
Gracias a la alta frecuencia de actualizaciones (últimos datos recibidos el 29 agosto, 2026), el canal mantiene la vigencia y un amplio alcance. La analítica demuestra que la audiencia interactúa activamente con el contenido, lo que lo convierte en un punto de referencia dentro de la categoría Educación.
INTERSECT and EXCEPT. Let’s take a closer look at how they work.
🔻 The INTERSECT Operator
The INTERSECT operator is used to find rows that are present in both queries. It works like the intersection of sets in mathematics, returning only those records that exist in both datasets.
Example:
SELECT column1, column2
FROM table1
INTERSECT
SELECT column1, column2
FROM table2;
This will return rows that appear in both table1 and table2.
Key Points:
- The INTERSECT operator automatically removes duplicate rows from the result.
- The selected columns must have compatible data types.
🔻 The EXCEPT Operator
The EXCEPT operator is used to find rows that are present in the first query but not in the second. This is similar to the difference between sets, returning only those records that exist in the first dataset but are missing from the second.
Example:
SELECT column1, column2
FROM table1
EXCEPT
SELECT column1, column2
FROM table2;
Here, the result will include rows that are in table1 but not in table2.
Key Points:
- The EXCEPT operator also removes duplicate rows from the result.
- As with INTERSECT, the columns must have compatible data types.
📊 What’s the Difference Between UNION, INTERSECT, and EXCEPT?
- UNION combines all rows from both queries, excluding duplicates.
- INTERSECT returns only the rows present in both queries.
- EXCEPT returns rows from the first query that are not found in the second.
📌 Real-Life Examples
1. Finding common customers. Use INTERSECT to identify customers who have made purchases both online and in physical stores.
2. Determining unique products. Use EXCEPT to find products that are sold in one store but not in another.
By using INTERSECT and EXCEPT, you can simplify data analysis and work more flexibly with sets, making it easier to solve tasks related to finding intersections and differences between datasets.
Happy querying!SELECT query.
Features
- Does not store data; it retrieves data from underlying tables.
- Simplifies complex queries.
Syntax
CREATE VIEW view_name AS
SELECT columns
FROM table_name
WHERE condition;
Example
Create a view to show high-salaried employees:
CREATE VIEW HighSalaryEmployees AS
SELECT name, salary
FROM employees
WHERE salary > 100000;
Use the view:
SELECT * FROM HighSalaryEmployees;
Interview Questions
1. What is the difference between a table and a view?
- A table stores data physically; a view does not.
2. Can you update data through a view?
- Yes, if the view is updatable (no joins, no aggregate functions, etc.).
3. What are the advantages of using views?
- Simplifies complex queries, enhances security, and provides abstraction.