Altering tables

suggest change

Let’s create two simple tables:

CREATE TABLE users (username text, email text);
CREATE TABLE simple_users () INHERITS (users);

Adding columns

ALTER TABLE simple_users ADD COLUMN password text;

simple_users

Column | Type — | — username | text email | text password | text

Adding the same column to the parent table will merge the definition of both columns:

ALTER TABLE users ADD COLUMN password text;
NOTICE: merging definition of column “password” for child “simple_users”

Dropping columns

Using our altered tables:

ALTER TABLE users DROP COLUMN password;

users

Column | Type — | — username | text email | text

simple_users

Column | Type — | — username | text email | text password | text

Since we first added the column to simple_users, PostgreSQL makes sure this column isn’t dropped.

Now if we had another child table, its password column would, of course, have been dropped.

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