Click 🚀 Start SQL Debugger above to inspect intermediate virtual tables at each line of execution.
Press ▶ Run Full Query to execute without stepping.
Run a SELECT query to inspect the internal B-Tree index traversal and execution plan.
Select a challenge and click Test Challenge to verify.
Window Ranking Functions
ROW_NUMBER() OVER (PARTITION BY d ORDER BY sal DESC)
DENSE_RANK() OVER (PARTITION BY d ORDER BY sal DESC)
Time Series & Offsets
LAG(val, 1) OVER (ORDER BY date_col)
LEAD(val, 1) OVER (ORDER BY date_col)
NULL Handling & Coalesce
COALESCE(comm, 0)
NULLIF(a, b)
