SQL
From first queries to CTEs and window functions, through many practice exercises on real tables.
SQL and data engineering mentor in Colombia
Cristian Correa has taught SQL, dbt, Python and data modeling to people starting in data and to working analysts. Nine of them wrote about it.
9
written testimonials from mentees
5
topics: SQL, dbt, Python, modeling, statistics
2023
first mentoring testimonial
8
years in data and software
What it is – 01
What does a data engineering mentor do?
A data engineering mentor teaches people to work with real data, SQL, data warehouses, dbt, Python, modeling and orchestration, through practice on concrete cases until they can do it on their own.
Cristian Correa mentored analysts and engineers in Colombia and Latin America in 2023 and 2024, alongside his data engineering work at Platzi and Rappi. One mentee, Mitchel Pinzón, joined the Datalytics Data School after his SQL classes and now works as a data engineer.
Topics – 02
What his mentees learned
Data warehouses and dbt
How warehouses are organized and how dbt models, tests and documents them.
Python for data engineering
Scripts and pipelines that move and clean data.
Data modeling and orchestration
Modeling for analytics and scheduling pipelines, explained with concrete use cases.
Statistics and data analysis
Statistics, data visualization and Excel for analysis, taught by a statistician.
Free – 03
SQL4All, free SQL for Spanish speakers
Cristian Correa also built SQL4All (sql4all.org), a free interactive SQL course in Spanish that runs a real Postgres database in the browser, so anyone can practice without installing anything.
In their own words
“Las clases de SQL fueron fundamentales en mi ruta de aprendizaje para convertirme en ingeniera de datos. Gracias a lo que aprendí, logré ingresar a una convocatoria de Data School en Datalytics y actualmente soy ingeniera de datos.
Las clases de SQL fueron muy dinámicas, claras, realizamos muchos ejercicios de práctica y eso permitió que el aprendizaje fuera más consiente y profundo.”
“Las asesorías de Cristian han sido sumamente valiosas. He aprendido un montón sobre el manejo de bodegas de datos, herramientas avanzadas como dbt, Python para la ingeniería de datos y orquestación de datos. Cristian realmente sabe lo que hace y su experiencia como Senior se nota.
Es muy claro al explicar y su habilidad para enseñar cosas complicadas de manera sencilla hacen que aprender de él sea una experiencia muy enriquecedora.”
“Truly grateful for the mentorships. Every space make all the concepts easy to understand and translate it to examples to get involved with it. I've learnt about SQL, Python, data viz and Excel for data analysis, so I honestly recommend him as an excellent mentor.”
“Gracias a su mentoría pude aprender sobre data modeling y orchestration. Fue una mentoría bastante enriquecedora, porque no solo aprendí sobre el uso de tecnologías para dichos fines, sino que al ejemplificar con posibles casos de uso, pude asociar más facilmente los potenciales escenarios.”
“Me gustaron mucho las clases, son muy prácticas, las recomiendo. Cristian busca varias formas o recursos para lograr que entiendas el tema de forma sencilla. Aprendí temas enfocados a estadística.”
“Me ayudó con un proyecto que tenía en SQL, con él descubrí los CTE, lo que me ayuda mucho a la hora de trabajar. Además ha demostrado ser muy responsable. Lo recomiendo.”
“Cristian me ayudó demasiado a entender SQL, es super paciente, explica super bien y si es necesario él repite la explicación hasta que entiendas.”
“Fue el mejor tutor que tuve, él me explicó muy bien y fue paciente. Para alguien principiante como yo fue una persona adecuada para enseñar.”
“No pude haber encontrado alguien mejor en SQL. Me ayudó a responder varios ejercicios en tiempo récord.”
Questions – 04
Questions
What does a data engineering mentor do?
A data engineering mentor teaches people to work with real data, SQL, data warehouses, dbt, Python, modeling and orchestration, through practice on concrete cases until they can do it on their own.
Mentor, tutor, teacher or coach: what's the difference?
A teacher follows a course. A tutor helps with specific exercises. A coach works on habits and career. A mentor does a bit of all three from real experience in the field. Mentees describe Cristian Correa as all of them: tutor for SQL exercises, teacher for dbt and data modeling, and mentor for a career in data.
What did Cristian Correa teach?
SQL, including CTEs; data warehouses and dbt; Python for data engineering; data modeling and orchestration; and statistics, data visualization and Excel for data analysis.
Did his mentees get data jobs?
Some did. Mitchel Pinzón wrote that his SQL classes got her into the Data School at Datalytics and that she now works there as a data engineer. Other mentees work as analysts and engineers at Paak S.A.S. and Rappi.
Is he a good mentor for beginners?
Mentees who started from zero say so: he is patient, repeats an explanation until it lands and teaches with practice exercises. Eliana Niño called him the best tutor she had as a beginner.
Where can I learn SQL for free in Spanish?
SQL4All (sql4all.org), the free interactive SQL course Cristian Correa built for Spanish speakers, with a Postgres database that runs in the browser.