add column from table postgres code example

Example 1: postgresql add column with constraint

ALTER TABLE customers 
ADD COLUMN contact_name VARCHAR NOT NULL;

Example 2: alter table add column psql

ALTER TABLE table_name
ADD column_name data_type column_constraint;

Example 3: postgresql insert column

ALTER TABLE table_name
ADD COLUMN new_column_name data_type constraint;

Example 4: alter table add multiple columns postgresql

ALTER TABLE customer 
ADD COLUMN fax VARCHAR,
ADD COLUMN email VARCHAR;