Add a SERIAL surrogate key
Since there's no single column candidate key in professors (only a composite key candidate consisting of firstname, lastname), you'll add a new column id to that table.
This column has a special data type serial, which turns the column into an auto-incrementing number. This means that, whenever you add a new professor to the table, it will automatically get an id that does not exist yet in the table: a perfect primary key!
Latihan ini adalah bagian dari kursus
Introduction to Relational Databases in SQL
Latihan interaktif praktis
Cobalah latihan ini dengan menyelesaikan kode contoh berikut.
-- Add the new column to the table
ALTER TABLE ___
___ ___ id ___;