Lesson Beginner

SQL syntax

Good SQL is rarely about clever tricks.
Most of the time, it is about getting structure right: what to select, where it comes from, how it is filtered, and how it is ordered.

Think in Clauses, Not in One Long Sentence #

A query is built from clauses.
Each clause has a job, and clauses are easier to reason about when you read them as building blocks instead of as one giant statement.

Core Clauses You Will Use Every Day #

Clause	Purpose
SELECT	Choose columns to return
FROM	Choose source table(s)
WHERE	Filter rows before grouping
GROUP BY	Aggregate by key(s)
HAVING	Filter after aggregation
ORDER BY	Sort final output
LIMIT	Restrict row count

sql

SELECT column_list
FROM table_name
WHERE condition
GROUP BY grouping_columns
HAVING aggregate_condition
ORDER BY sort_columns
LIMIT n;

Why Clause Order Feels Weird at First #

SQL is written in one order and evaluated in another.
That mismatch is normal, and understanding it will prevent a lot of confusion:

FROM -> WHERE -> GROUP BY -> HAVING -> SELECT -> ORDER BY -> LIMIT

This mental model helps explain many beginner errors, especially around aggregation and filtering.

Run and Tweak #

Run this query, then change one clause at a time to see how the output changes:

Loading SQL editor...

Knowledge check #

3 questions

0 / 3 answered

Which of these is the standard clause order when writing a query?
SQL keywords like SELECT and FROM are:
How do you write a single-line comment in SQL?

Next Step #

Continue to SQL datatypes to understand how value types affect filtering, sorting, and calculations.