May I ask if you can use constraint to set limited so that one member (clen) can play for just one club (klub) ? My point is that this does not happen, for example: id_member = 1 && id_club = 1; ...., id_member = 1 && id_club = 2; What I have does not seem entirely appropriate to me here and it occurs to me that it does not solve this problem.
ALTER TABLE member ADD CONSTRAINT unq_member_and_club UNIQUE(id_member, id_club); Is it possible to solve this with integrity constraints in the create script at all or are triggers used for it? I am a part of my create script.
Schema
Create script
CREATE TABLE club ( id_club SERIAL NOT NULL, nazev VARCHAR(256) NOT NULL, datum_zalozeni VARCHAR(256) NOT NULL ); ALTER TABLE club ADD CONSTRAINT pk_club PRIMARY KEY (id_club); ALTER TABLE club ADD CONSTRAINT uc_club_nazev UNIQUE (nazev); CREATE TABLE coach ( id_member INTEGER NOT NULL ); ALTER TABLE coach ADD CONSTRAINT pk_coach PRIMARY KEY (id_member); CREATE TABLE member ( id_member SERIAL NOT NULL, id_club INTEGER NOT NULL, jmeno VARCHAR(256) NOT NULL, prijmeni VARCHAR(256) NOT NULL, narodnost VARCHAR(256) NOT NULL, datum_narozeni VARCHAR(256) NOT NULL ); ALTER TABLE member ADD CONSTRAINT pk_member PRIMARY KEY (id_member); CREATE TABLE owner ( id_member INTEGER NOT NULL ); ALTER TABLE owner ADD CONSTRAINT pk_owner PRIMARY KEY (id_member); CREATE TABLE player ( id_member INTEGER NOT NULL, cislo VARCHAR(256) NOT NULL, post VARCHAR(256) NOT NULL ); ALTER TABLE player ADD CONSTRAINT pk_player PRIMARY KEY (id_member); ALTER TABLE coach ADD CONSTRAINT fk_coach_member FOREIGN KEY (id_member) REFERENCES member (id_member) ON DELETE CASCADE; ALTER TABLE member ADD CONSTRAINT fk_member_club FOREIGN KEY (id_club) REFERENCES club (id_club) ON DELETE CASCADE; ALTER TABLE owner ADD CONSTRAINT fk_owner_member FOREIGN KEY (id_member) REFERENCES member (id_member) ON DELETE CASCADE; ALTER TABLE player ADD CONSTRAINT fk_player_member FOREIGN KEY (id_member) REFERENCES member (id_member) ON DELETE CASCADE; enter code here enter code here 
