TryBench
Learn SQL From Zero With Real Data
Practice real SQL queries in your browser, from your first SELECT to JOINs, CTEs and window functions.
19 short lessons. Beginners who want a job-ready data skill, and analysts who want to fill gaps. Each lesson takes about two minutes: read the idea, try it yourself, and get instant checks.
Start here: foundation lessons (7)
No experience needed. These lessons build the basics step by step.
- Choosing Columns with SELECTQuery database tables and retrieve specific columns instead of dumping unnecessary data.
- Filtering Rows with WHEREUse WHERE clauses to isolate specific records and exclude irrelevant or cancelled data.
- Sorting & Capping with LIMITOrder query results and cap row counts to find top transactions quickly.
- Aggregating Totals with COUNT & SUMCalculate high-level summary metrics across thousands of rows in a single query.
- SQL INNER JOIN Explained for BeginnersCombine data from multiple tables using shared primary and foreign key IDs.
- Combining Conditions: AND, OR, IN & LIKECombine several filters in one WHERE clause to find exactly the rows a business question needs.
- Unique Values & AveragesUse DISTINCT, AVG, MIN, and MAX to describe a dataset in a single summary row.
Go further: practitioner lessons (12)
Real workplace tasks that build on the foundation.
- SQL COALESCE Example: Sum Totals With NULL ValuesLearn how SELECT, FROM, WHERE, and COALESCE prevent blank values from ruining database calculations.
- Filtering Only What MattersPick exactly the rows you want—so surprise categories don't sneak in.
- SQL LEFT JOIN Example: Keep Every CustomerJoin database tables without accidentally losing records or multiplying totals.
- Counting Unique RecordsCount unique individuals instead of duplicate transactions in summary reports.
- SQL HAVING vs WHERE Explained With ExamplesFilter raw records with WHERE and filter calculated totals with HAVING.
- Custom Category BucketsSegment numerical data into business tiers like High, Medium, and Low with CASE WHEN.
- Month-by-Month Trends & SQL DialectsGroup timestamps into uniform monthly buckets using DATE_TRUNC or strftime across different SQL dialects.
- Finding Top PerformersRank and retrieve top-N records without pulling millions of unnecessary rows.
- Crash-Proof DivisionPrevent query crashes and broken dashboards by guarding against division by zero and preserving decimal precision.
- SQL Window Function Running Total ExampleCompute running day-by-day totals without complex self-joins using SQL Window Functions.
- SQL CTE Example: Find Above-Average CustomersBreak a hard question into named steps with WITH, then compare each group to the overall average.
- SQL ROW_NUMBER PARTITION BY: Top N Per GroupUse ROW_NUMBER with PARTITION BY to find the top record inside every group.
Earn a certificate
Finish the lessons and claim a certificate with a unique ID that anyone can verify online. Share it on LinkedIn or add it to your CV.