Watch a SQL Query run.

QueryTrace plays your statement over live tables in the browser and shows what each clause did to the rows.

Open the tracer Open the tracer

SELECT V.VENUE_NAME, SUM(R.SEATS) AS 'Saturday Seats'FROM VENUE V

Wires run along VENUE_ID and the matched rows light up on both tables.

QueryTrace at the JOIN stage: wires connect VENUE_ID between the VENUE and SCREENING tables and matched rows are lit.

Every clause shows its work.

Joined

The RESERVATION table at the JOIN stage with matched rows lit.

Filtered

The RESERVATION table at the WHERE stage with failing rows faded.

Grouped

The RESERVATION table at the GROUP BY stage, each row tinted by venue.

Traced

The RESERVATION table with the five rows behind one result outlined in mint.

Nineteen lessons.

Each lesson is one query over a small fictional dataset. Open one and step through it.

Foundations

1. Choose result columnsHarbor ferry routes 2. Filter individual rows with WHERECoastal research survey 3. Combine conditionsHarbor ferry routes 4. Calculate and sortHarbor ferry routes 5. Match patterns and rangesIndependent film festival 6. Keep unique results with DISTINCTIndependent film festival 7. Label a combined text fieldNight observatory 8. Summarize a set of rowsCoastal research survey 9. Find missing valuesCoastal research survey 10. Aggregate within groupsIndependent film festival 11. Filter completed groups with HAVINGOrchard plot map

Combining data

12. Match related rows with JOINIndependent film festival 13. Match tables through WHERENight observatory 14. Preserve unmatched rowsIndependent film festival 15. Trace a complete query pipelineIndependent film festival 16. Chain multiple relationshipsCoastal research survey 17. Give one table two rolesOrchard plot map 18. Stack compatible resultsIndependent film festival 19. Feed one query into anotherHarbor ferry routes

Your own schema works too.

Paste the CREATE TABLE statements from your database. Exports from PostgreSQL and SQL Server paste in as they are, and so do MySQL and Oracle.

Everything runs on SQLite compiled to WebAssembly, inside the tab. Nothing you type is sent anywhere.

The schema dialog: five preloaded databases and a text area for your own CREATE TABLE statements.

The tracer opens on a four-table join you can step through right now.

Open the tracer Open the tracer