Vol. I · A Postgres HandbookTwelve chapters · · 756 queries

The Query & the Schema

A reading-room reference for writing PostgreSQL by hand — selects to window functions, with the schema in plain view.

EasyBasic SELECT

Remove a NOT NULL constraint

SQL

ALTER TABLE employees 
ALTER COLUMN email DROP NOT NULL;

Tested against PostgreSQL 16

Note

“Allows the column to accept NULL values again.