Answers for "POSTGRESS FOREIGN KEY SYNTAX"

postgres add foreign key to existing table

ALTER TABLE tblA ADD COLUMN colA VARCHAR(10); /* 1st add column */
ALTER TABLE tblA ADD CONSTRAINT colA /* Make colA on tblA a foreign key */
FOREIGN KEY (colA) REFERENCES tblB (colB); /* colB must be a pk on tblB*/

postgres add foreign key alter table

CREATE TABLE orders (
    order_id SERIAL,
    dish_name TEXT,
    customer_id INTEGER REFERENCES customers (id)
);