Below is the syntax to add a new column to an existing table in Postgres database.
ALTER TABLE table_name ADD COLUMN column_name datatype;
Example:
ALTER TABLE person ADD COLUMN email varchar(100);
Syntax to add multiple columns to a table:
ALTER TABLE table_name ADD COLUMN column_name1 datatype1, ADD COLUMN column_name2 datatype2, ADD COLUMN column_name3 datatype3;
Example:
ALTER TABLE employee ADD COLUMN salary integer, ADD COLUMN email varchar2(100), ADD COLUMN title varchar2(100);
