Tables, Rows, Columns — and Your First Query

Almost every technical or analytics interview reaches SQL at some point. It usually starts the same way: the interviewer shows a small table and asks what a query returns. In this lesson you meet the online shop we use for the whole course, see what a table is made of, and write and run your first q

A table is a tidy grid: each row is one item, each column is one attribute, and SELECT … FROM pulls out the columns you ask for.

Table: A collection of data about one kind of thing, arranged in rows and columns.
Row: One record in a table — a single item, such as one customer.
Column: One attribute every row has, such as city.
Primary key: A column whose value differs in every row and is never empty, so it identifies exactly one row.
Query: A question written in SQL whose answer comes back as a table.