You can do 80% of Data Engineering work just by using 20% of SQL Queries

Here are the top SQL Keywords/Functions👇🏻

💡SELECT:
Fetch billions of rows for analysis

💡WHERE CLAUSE:
Well, we don't need all the data! filter by date? region?

💡ORDER BY:
I want to see data in a specific order by date or employee name

💡Aggregation function (MIN, MAX, AVG, COUNT)
For analysis, I have to get the total revenue, we can use SUM for that

Like this, there are many functions MAX, MIN, AVG, and COUNT for aggregation.

💡 GROUP BY:
We can't use the aggregation function without GROUP BY if we are using multiple columns.

Why use it?
Get SUM/AVG revenue of product by category/date/customer

💡 JOINS (INNER, LEFT, RIGHT, FULL, SELF)
The data is stored across multiple tables.

We use different joins to bring all of these data together and do the analysis.

💡 Common Table Expressions (CTE):
Many times you'll fetch some data from multiple tables and apply more logic on top of the result you get.

CTE allows you to define a query and refer to it multiple times within a SQL statement.

I USE THIS DAILY!

💡 Working with DATETIME/TIMESTAMP
DATETIME is the backbone of every analysis you'll do, fun part is they are messy.

They come in string format, the timezone is not attached, and many more

Handling them is a skill

💡 Numbering functions (RANK, DENSE_RANK, ROW_NUMBER)

JUST LEARN THESE!

You'll get this in the interview also and it helps you to solve many problems in the world

>> There are many others <<
IFNULL
COALESCE
CASTING
MERGE STATEMENT
QUALIFY

Did I miss anything?