SQLite: Preventing Duplicate Rows

Question

CREATE TABLE Permission ( 
    permissionID INTEGER PRIMARY KEY UNIQUE,
    user         INTEGER
    location     INTEGER 
);

I don\'t want to have

Answer 1

Declare a unique constraint on (user, location).

CREATE TABLE Permission (
    permissionID integer primary key,
    user integer not null,
    location integer not null,
    unique (user, location)
);

sqlite> insert into Permission (user, location) values (1, 2);
sqlite> insert into Permission (user, location) values (1, 2);
Error: UNIQUE constraint failed: Permission.user, Permission.location