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SQL / CHAPTER 01
SQL
Queries.
Learn SQL with real tables and PostgreSQL in your browser. Learn and Practice per topic, separate challenges.
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Lesson with explanation and a guided task. Theory stays readable; completion requires a passing solution.
Challenges are optional and do not block the next chapter.
12 lessons available
The foundations behind your ideas.
- 01Start lesson
Tables and SELECT
Tables and SELECT
- 02Open lesson
Selecting columns · Locked
Selecting columns
- 03Open lesson
Aliases with AS · Locked
Aliases with AS
- 04Open lesson
Filtering with WHERE · Locked
Filtering with WHERE
- 05Open lesson
AND, OR, NOT and parentheses · Locked
AND, OR, NOT and parentheses
- 06Open lesson
IN and BETWEEN · Locked
IN and BETWEEN
- 07Open lesson
Patterns with LIKE · Locked
Patterns with LIKE
- 08Open lesson
Missing data: NULL · Locked
Missing data: NULL
- 09Open lesson
Distinct results · Locked
Distinct results
- 10Open lesson
Ordering results · Locked
Ordering results
- 11Open lesson
The first N rows · Locked
The first N rows
- 12Open lesson
Calculated columns · Locked
Calculated columns