Daily challengeStill lockedFinish your first module.

Module 1

First day

You are a freelance data analyst, and every day brings a new client. Today: Bonen & Co. Rosa, the owner, has a database full of customers, coffee and orders. Only nobody knows how to get anything out of it. Until today.

  1. 1
    What is a table?
  2. Picking one column
  3. Several columns
  4. A little taster
  5. Renaming columns
  6. Arithmetic in SELECT
  7. BossThe banker pays a visit

Module 2

Second day

Rewind still rents out films, and it has a loyal crowd of members. Owner Vic keeps everything in a database, but still searches it by hand. You're about to put an end to that.

  1. Filtering rows with WHERE
  2. Greater, smaller, not equal
  3. Combining conditions
  4. A list with IN
  5. From … to with BETWEEN
  6. Searching text with LIKE
  7. Missing values with IS NULL
  8. BossThe film marathon

Module 3

Third day

In three weeks Zomerklank opens its gates. Festival boss Noor has the line-up, the stages and the ticket sales neatly in a database, but everything is jumbled. Posters, timetables and sponsor reports all need to be in order. Time to bring order to the chaos.

  1. Sorting with ORDER BY
  2. Sorting on several columns
  3. Removing duplicates with DISTINCT
  4. BossThe festival booklet

Module 4

Fourth day

De Trapper rents out city bikes, e-bikes, cargo bikes and tandems to tourists in Bruges. After the summer, owner Lien has just one question: "So what did it actually bring in?" Thirty rentals, fourteen repairs and an accountant who is waiting. Time to do the maths.

  1. Counting with COUNT
  2. Adding up with SUM
  3. Averages with AVG
  4. The smallest and the largest
  5. Per group with GROUP BY
  6. Filtering groups with HAVING
  7. BossThe annual report

Module 5

Fifth day

FC De Kraaien has six teams, a handful of coaches and a club secretary who keeps track of it all: Yasmine. Players, teams, matches and goals sit neatly in separate tables. The only snag: the answers she's after are always in two tables at once.

  1. Keys connect tables
  2. Linking tables with JOIN
  3. Writing less with aliases
  4. Forget no one with LEFT JOIN
  5. RIGHT and FULL JOIN
  6. More than two tables
  7. Joining a table to itself
  8. BossThe club gala

Module 6

Sixth day

Librarian Sanne manages thousands of loans, but over the years her database has become a bit messy: genres with and without capitals, names with stray spaces, books that are weeks overdue. Her questions can't be answered with one simple WHERE.

  1. Working with text
  2. Calculating with dates
  3. Choosing with CASE
  4. A question inside a question
  5. Does it exist? EXISTS and the NOT IN trap
  6. Readable with WITH
  7. BossThe report for the city

Module 7

Seventh day

Jens the baker opens his web shop next week. Yule logs, croissants, loyalty points: it is all in a database already. Only something changes every day. New products, new prices, cancelled orders. Until now you only read data. Today you change it.

  1. New in the shop window
  2. Adjusting prices
  3. Tidying up
  4. All or nothing
  5. BossThe Christmas rush

Module 8

Eighth day

Five days of racing, sixteen riders, four teams. Race director Griet has every result in a database, but each evening the press wants to know the same thing: who leads, by how much, and who wears which jersey? Building classifications: a job for the heaviest SQL you have seen so far.

  1. A number for every row
  2. Same time
  3. Per team, per stage
  4. The standings
  5. Everything on one list
  6. BossThe podium in Halle

Badges