Working in mysql with foreign keys -

i want create mysql database foreign keys. when insert test data notice when in tables tblcontact , tbladdress foreign key null. know basic question can give suggestions?

create table tblcustomers ( customerid int not null auto_increment primary key, firstname varchar(30) not null, lastname varchar(30) not null, vat varchar(30) not null, customervisible varchar(1) not null default 't' );    create table tblcontact ( contactid int not null  auto_increment primary key, email varchar(100), phone varchar(100), customerid int, constraint fk_customerid foreign key (customerid) references tblcustomers(customerid)  );  create table tbladdress ( addressid int not null  auto_increment primary key, street varchar(100), housenumber varchar(15), city varchar (100), country varchar (100), customerid int, constraint fk_customerida  foreign key (customerid) references tblcustomers(customerid) );   insert tblcustomers (firstname, lastname,vat) values ("john","doe","uv45856855"); insert tblcontact (email, phone) values ("0000001","johndoe@gmail.com"); insert tbladdress (street,housenumber,city,country) values ("berkenlaan","1a","harelbeke","belgie"); 

you misunderstood concept of foreign keys.. foreign key key used link 2 tables together.. in order relate particular row parent row should enter reference (primary key of parent) in child.

its not automatic.. have enter customerid of tblcustomer in tbladdress , tblcontact manually contain dependency.

you didnt in code.. thats why getting null. how mysql know data putting in tbladdress , tblcontact related specific customer?

if want happen automatically can create trigger using last_insert_id().

example:-

create trigger tbladdress_auto_insert after insert on `tbladdress`  each row begin      insert tbladdress (customerid) values (last_insert_id()); end; 

similarly tblcontact.

hth