Hello list, I have a rather simple parent/child structure, but I don't know how to formulate my problem in SQL.
Question: I want to know all those parent.id values where there are at least two children with the same X value. Put differently: Get me all the parents whose children do not have pairwise disjoint X values. SQL: create table parent ( id number ); alter table parent add constraint parent_pk primary key (id); create table child ( x number, parent_fk number ); alter table child add constraint FK foreign key (parent_fk) references parent(id); Some data: insert into parent values (1); insert into parent values (2); insert into child values (10,1); insert into child values (20,1); insert into child values (20,1); insert into child values (100,2); insert into child values (200,2); Expected response: 1, because of the two 20 entries. Any ideas appreciated. Regards, Matthias -- MaxDB Discussion Mailing List For list archives: http://lists.mysql.com/maxdb To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
