How do I ALTER a PostgreSQL table and make a column unique?

I figured it out from the PostgreSQL docs, the exact syntax is:

ALTER TABLE the_table ADD CONSTRAINT constraint_name UNIQUE (thecolumn);

Thanks Fred.

Or, have the DB automatically assign a constraint name using:

ALTER TABLE foo ADD UNIQUE (thecolumn);

it's also possible to create a unique constraint of more than 1 column:

ALTER TABLE the_table 
    ADD CONSTRAINT constraint_name UNIQUE (column1, column2);

Related