this should result in empty tables.

Once worked under Oracle but now does not work under MS SQL Server 2005 and mysql

alter table pets_like_boys
drop constraint pets_like;

alter table girls_like_pets
drop constraint girls_like;

alter table boys_like_girls
drop constraint boys_like;

drop table pets_like_boys;
drop table boys_like_girls;
drop table girls_like_pets;

- first time start here

create table pets_like_boys (pets_name varchar(32), boys_name varchar(32),primary key (pets_name));
create table boys_like_girls (boys_name varchar(32), girls_name varchar(32),primary key (boys_name));
create table girls_like_pets (girls_name varchar(32), pets_name varchar(32),primary key (girls_name));

insert into pets_like_boys values('fluffy', 'sam');
insert into pets_like_boys values('rover', 'bob');
insert into pets_like_boys values('skippy', 'joe');

insert into boys_like_girls values('bob','jill');
insert into boys_like_girls values('sam','betty');
insert into boys_like_girls values('joe','sue');
insert into boys_like_girls values('george','jill');

insert into girls_like_pets values('sue','fluffy');
insert into girls_like_pets values('jill','skippy');
insert into girls_like_pets values('betty','rover');

alter table pets_like_boys
add constraint pets_like
foreign key (boys_name )
references boys_like_girls
on delete cascade;

alter table boys_like_girls
add constraint boys_like
foreign key (girls_name )
references girls_like_pets
on delete cascade;

alter table girls_like_pets
add constraint girls_like
foreign key (pets_name )
references pets_like_boys
on delete cascade;


select * from pets_like_boys;
select * from boys_like_girls;
select * from girls_like_pets;
delete from boys_like_girls where boys_name = 'bob';
select * from pets_like_boys;
select * from boys_like_girls;
select * from girls_like_pets;

ur doing it wrong lol

dey gots to be innodb tables, i bets your default is myisam

I am just starting to learn mysql

it's right there in the manual

since cascade is not a obscure constraint

obviously you are new to mysql

it's right there in da manual

I'm sure it is in the manual. I should have read all 15,000 pages before trying a select statement. That makes sense doesn't it?

OR

By mental telepathy I should have known about myisam and lookd it up before using a plain old cascade constraint. That makes sense doesn't it?


Again, why such an involved option change for a simple constraint?

This make the SQL non-standard/not portable.

Do you understand? This is a conceptual situation!

i conceptually understand that you are conceptually frustrated and you have my conceptual condolences

I am an amateur psych, philos, theolog!

Tell me something!

(1) briefly, what college degrees do you have?

(2) are you a programmer (C#, C++, PHP)?

(3) what are your strengths outside of (I suppose) sql

1) bachelor of science, university of toronto
2) no
3) sweet, sweet lovin

my turn to ask you some questions

1) how old are you
2) what country do you live in
3) please describe the application you are building

sorry!

engine=innodb didn't help

alter table pets_like_boys
drop constraint pets_like;

alter table girls_like_pets
drop constraint girls_like;

alter table boys_like_girls
drop constraint boys_like;

drop table pets_like_boys;
drop table boys_like_girls;
drop table girls_like_pets;

create table pets_like_boys (pets_name varchar(32), boys_name varchar(32),primary key (pets_name))engine=innodb;
create table boys_like_girls (boys_name varchar(32), girls_name varchar(32),primary key (boys_name))engine=innodb;
create table girls_like_pets (girls_name varchar(32), pets_name varchar(32),primary key (girls_name))engine=innodb;

insert into pets_like_boys values('fluffy', 'sam');
insert into pets_like_boys values('rover', 'bob');
insert into pets_like_boys values('skippy', 'joe');

insert into boys_like_girls values('bob','jill');
insert into boys_like_girls values('sam','betty');
insert into boys_like_girls values('joe','sue');
insert into boys_like_girls values('george','jill');

insert into girls_like_pets values('sue','fluffy');
insert into girls_like_pets values('jill','skippy');
insert into girls_like_pets values('betty','rover');

alter table pets_like_boys
add constraint pets_like
foreign key (boys_name )
references boys_like_girls
on delete cascade;

alter table boys_like_girls
add constraint boys_like
foreign key (girls_name )
references girls_like_pets
on delete cascade;

alter table girls_like_pets
add constraint girls_like
foreign key (pets_name )
references pets_like_boys
on delete cascade;


select * from pets_like_boys;
select * from boys_like_girls;
select * from girls_like_pets;
delete from boys_like_girls where boys_name = 'bob';
select * from pets_like_boys;
select * from boys_like_girls;
select * from girls_like_pets;

1) how old are you 67
2) what country do you live in USA
3) please describe the application you are building |this is an academic exercise

to get to know mysql after Oracle and MS SQL server

BTW I was going to ask! How old are you?

may I probe further? a question from my academics

(2) What normal form is violated here?
A telephone call is uniquely identified by telephone number and time of call. These candidate keys compose the composite primary key. There is an attribute/column “telephone location”

no research...just what you know