Databases and tables

A database stores information in tables. A table is a grid, a bit like a spreadsheet:

• each row is one record — for example, one student;
• each column is one field — for example, the student's name or score.

This course uses a small table called student. It has 5 records and 4 fields: id, name, form, and score.

Asking for data with SELECT

To read data from a table you write a query with SELECT.

The simplest query asks for every column of every row. The star * means "all columns":

• SELECT chooses the columns — * means all of them.
• FROM student says which table to read.

The database replies with a result table (also called a result set): the rows your query asked for.

A few rules

• Keywords like SELECT and FROM are often written in capitals so they stand out.
• End each statement with a semicolon ;.
• An empty cell is shown as NULL, which means "no value".

Now try it. Click Run to see the output, then Check answer.

Common mistakes

• End a query with a semicolon: SELECT ... FROM table;.
• SELECT * returns every column — name only the ones you need.