In Postgresql, force unique on combination of two columns

Create unique constraint that two numbers together CANNOT together be repeated:

ALTER TABLE someTable
ADD UNIQUE (col1, col2)

CREATE TABLE someTable (
    id serial PRIMARY KEY,
    col1 int NOT NULL,
    col2 int NOT NULL,
    UNIQUE (col1, col2)
)

autoincrement is not postgresql. You want a integer primary key generated always as identity (or serial if you use PG 9 or lower. serial was soft-deprecated in PG 10).

If col1 and col2 make a unique and can't be null then they make a good primary key:

CREATE TABLE someTable (
    col1 int NOT NULL,
    col2 int NOT NULL,
    PRIMARY KEY (col1, col2)
)

Seems like regular UNIQUE CONSTRAINT :)

CREATE TABLE example (
a integer,
b integer,
c integer,
UNIQUE (a, c));

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