Instruction
Speaking of fewer keyboard strokes, there is one more thing which may come in handy and make you write less: aliases for tables.
Imagine the following situation: we want to select many columns from two joined tables. You could, of course, write it like this:
SELECT person.id, person.name, person.year, car.id, car.name, car.year FROM person JOIN car ON person.id = car.owner_id;
Takes a lot of writing, doesn't it? All those column names together with their table names... Fortunately, there is a way to make things simpler: we can introduce new temporary names (called aliases) for our tables:
SELECT p.id, p.name, p.year, c.id, c.name, c.year FROM person AS p JOIN car AS c ON p.id = c.owner_id;
As you can see, after the table names in the FROM clause, we used the keyword AS. It indicates that whatever comes next will become the new, temporary name (alias) for the table. Thanks to this, we can save our fingers a little bit and write shorter names for our tables.
Exercise
Use INNER JOIN on the tables room and equipment so that all pieces of equipment are shown with their room data. Use table aliases r and e. Select the columns id and name from the table equipment, as well as room_number and beds from the table room.
Stuck? Here's a hint!
Type:
SELECT e.id, e.name, r.room_number, r.beds FROM equipment AS e INNER JOIN room AS r ON e.room_id = r.id;
