Learn SQL · Practice notebook Interactive DB lab

SQL practice, one query at a time

Write real SQL on a library of famous books, from Sherlock Holmes to Harry Potter, right in your browser. Every answer is checked instantly, with a plain-English explanation when it's wrong. Know Excel already? Each lesson shows the formula that does the same job.

27 lessons ready
Runs on SQLite in your browser
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STEP 01 3 of 3 ready

Start here: SELECT

Ask a table for the columns you want.

STEP 02 5 of 5 ready

Picking rows

Keep only the rows you need with WHERE.

STEP 03 2 of 2 ready

Sorting

Put rows in order and keep the top few.

STEP 04 3 of 3 ready

Totals and groups

Count, add up and average, per group.

STEP 05 4 of 4 ready

Joining tables

Bring two tables together on a shared column.

STEP 06 3 of 3 ready

CASE and functions

Labels, text and dates.

STEP 07 2 of 2 ready

Queries inside queries

Use one result inside another.

STEP 08 3 of 3 ready

Window functions

Rankings and running totals, a favourite in interviews.

STEP 09 2 of 2 ready

Changing data

Add, change and remove rows.

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