Great. In the previous example, we provided column names together with the tables they are a part of. It's good practice, but you only need to do it when there is a chance to confuse them. If there are two different columns under the same name in two different tables, then you have to specify the tables. If the name of the column is unique, though, you may omit the table name.
ON person.id = owner_id;
There is only one column named
name and one only column named
model in the tables
car, so we could provide their names without giving information about the tables they come from. Similarly, there is only one column named
owner_id – it is only in the table
car, so we can omit the name of the table.
When we refer to column
id from table
person, though, we must write the table name as well (
person.id), because there is another column under the name
id in table