Example of through table and constraints

apt.sql

CREATE TABLE states (
    id INT PRIMARY KEY,
    statename VARCHAR(50)
);

CREATE TABLE disclaimers (
    id INT PRIMARY KEY,
    disclaimertxt VARCHAR(50)
);

CREATE TABLE client (
    id INT PRIMARY KEY,
    name VARCHAR(50)
);

CREATE TABLE state_disclaimer (
    id INT PRIMARY KEY,
    client_id int,
    states_id int,
    disclaimers_id int,
    Foreign key (client_id) references client(id),
    Foreign key (states_id) references states(id),
    Foreign key (disclaimers_id) references disclaimers(id)
);

SELECT client."name", disclaimers.disclaimertxt, states.statename  from state_disclaimer sd 
join client on sd.client_id = client.id
join states on sd.states_id = states.id 
join disclaimers on sd.disclaimers_id = disclaimers.id;

ALTER TABLE disclaimers
ADD CONSTRAINT uc_nodupe_disclaimers UNIQUE (disclaimertxt);

ALTER TABLE state_disclaimer 
ADD CONSTRAINT uc_nodupe_disclaimer_state UNIQUE (client_id, states_id, disclaimers_id);