If you want to do quick searches in a database, it is best to have a good understanding of the way in which the tables of the database refer to each other. The database scheme has been drawn up for this purpose. It’s up to you to examine this thoroughly and find out the meaning of the arrows. Usually, for clarity, next to each column is its type.

De database contains these tables:

• CUSTOMER: customer information (address, email …)
• DISCOUNT_CODE: discount dependant on discount code
• MANUFACTURER: manufacturer information (address, email …)
• MICRO_MARKET: regions which form a micro market
• PRODUCT: products (price, description …)
• PRODUCT_CODE: product code indicates the different kinds of products
• PURCHASE_ORDER: purchase information

Tip to compose queries

First determine which columns from which tables you need to consult (either to write out, or to solve a function, or to check a condition).

Database schema always at hand 👉

The database schema associated with the exercise can be called up for each exercise by clicking on the database icon in the top right corner. Unfortunately this does not work in the VS Code extension, only on Dodona itself. You can of course also download that image¹.

Order of columns

The order of the columns does not matter in queries in Dodona.