PostgreSQL -How to Drop a NOT NULL Constraint
To drop a NOT NULL constraint from an existing column in a PostgreSQL table, you can use the ALTER TABLE statement with the ALTER COLUMN clause. Here’s the basic syntax:
ALTER TABLE table_name ALTER COLUMN column_name DROP NOT NULL;where table_name is the name of the table containing the column and column_name is the name of the column from which you want to remove the NOT NULL constraint.
Here’s an example of how to use this syntax to remove a NOT NULL constraint from an existing column:
ALTER TABLE users ALTER COLUMN email DROP NOT NULL;After executing this SQL statement, the “email” column in the “users” table will no longer have the NOT NULL constraint, and you will be able to insert NULL values into that column if necessary.