04-create-a-custom-enum-type.md

Create a Custom Enum Type

Data integrity is something you should always have in mind

We can ensure integrity by adding constraints to our tables.

A powerful feature of SQL is the ability to create our own types.

  create type user_status as enum ('member', 'instructor', 'developer');
  CREATE TYPE

We create a data type called user_status as an enum and give it the string options of member, instructor, developer:

We can then add a column on our users table using this newly create type:

  postgres=# alter table users add column status user_status 

Now we can update a users status using our custom user_status type:

  postgres =# update users set status = 'instructor' where first_name = 'Lucie'; 

Using a custom enum will save us from misspellings and data errors since it requires that we use one of the strings we previously defined.