-- [PUMPS] create table pumps ( id varchar(32) primary key references _link(id) , node1 varchar(32) references _node(id) not null , node2 varchar(32) references _node(id) not null , power numeric , head varchar(32) references _curve(id) , speed numeric , pattern varchar(32) references _pattern(id) , check (power is not null or head is not null) , check ((power is not null and head is not null) is false) );