SQL Studio

🇫🇷 Version française : LISEZMOI.md

▶️ Launch SQL Studio — ready to use, demo database included.

A complete SQL interpreter running in your browser — no server, no dependency, one single HTML file.

User interface in French. Detailed documentation (French): sql_studio_doc.odt (LibreOffice Writer).

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Origin

The embedded database is a small teaching database freely copied from the picture of a DGSE (French intelligence service) quiz. Three tables, natural joins, deliberate NULLs — everything needed to learn SQL without friction.

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What it is

A teaching tool to learn and practise SQL, fully standalone. No Node.js. No Python. No CDN. No framework. Open the file in Firefox or Chrome — it is ready.

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Features

Feature	Description
SQL engine	SQL interpreter in plain JavaScript, in-memory data
Table explorer	Columns, types and data preview; SELECT * and DROP buttons per table
Keyword palette	One-click insertion of keywords and functions, grouped by family
Editor	Run with the button or Ctrl+Enter
Training mode	15 exercises over 10 levels, progressive hints and solutions, a lesson per level
Import / export	Import a CSV as a table, export the last result as CSV
Persistence	Database and progress kept in the browser's localStorage

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The SQL engine

This is the centrepiece. A SQL interpreter written in plain JavaScript that runs real queries on real in-memory data.

Supported queries:

• SELECT with named columns, AS aliases, *
• SELECT DISTINCT
• FROM with table aliases
• INNER JOIN and LEFT JOIN (with ON and NULL handling)
• Multiple joins (3 tables or more)
• WHERE with AND, OR, NOT, IN, NOT IN, BETWEEN, IS NULL, IS NOT NULL, operators = != > < >= <=
• CASE WHEN ... THEN ... ELSE ... END with arithmetic (+)
• Multi-column ORDER BY ASC / DESC
• LIMIT

Functions:

• COALESCE, CONCAT
• DATE, STRFTIME
• Spatial: ST_MakePoint(lon, lat), ST_X, ST_Y, ST_SRID, ST_GeometryType, ST_IsEmpty

Supported DDL/DML:

• CREATE TABLE
• DROP TABLE
• INSERT INTO ... VALUES
• UPDATE ... SET ... WHERE
• DELETE FROM ... WHERE

What the engine does well:

NULLs are handled correctly. A LEFT JOIN on a NULL foreign key keeps the row with the right-hand columns set to NULL — exactly like a real DBMS. CASE WHEN scoring adds several expressions cleanly. Table aliases are resolved in ON and WHERE conditions without ambiguity.

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Training mode

15 progressive exercises over 10 levels:

Level	Topic	Questions
1	SELECT	1
2	WHERE	1
3	AND / OR / IS NULL	1
4	DISTINCT · ORDER BY	2
5	INNER JOIN	2
6	LEFT JOIN	2
7	3 tables	2
8	CASE WHEN	2
9	INSERT	1
10	CREATE TABLE	1

Checking is done on the result, not on the syntax. Two different queries giving the same output are both accepted.

Levels 4 to 8: after 5 errors → hint. After 10 errors → solution + the question rephrased differently.

Progress is saved in localStorage — it survives a reload.

Each level has a lesson bubble (💡 button) with examples.

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Import / Export

• ⬇ démo: loads the DGSE database (3 tables)
• ↑ CSV: imports any .csv file as a new table, types detected automatically
• ↓ CSV: exports the result of the last SELECT query
• ✕ reset: clears everything

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Usage

Open the link above, or download sql_studio.html and open it in a browser.

No installation. No server. Works offline.

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History

Version	Change
2.1	Published version: SQL engine, Training mode, CSV import / export
2.2	Old copy pasted at the end of the file removed (duplicated interface and script)
2.3	AZS visual identity (slate / amber / cyan palette, AZS mark linking back to www.azs.fr, system fonts); stacked layout on small screens

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License

Free of rights. Copy, modify, redistribute.