mysql - SQL - many to many table wont work -

#1005 - can't create table 'ass1 lol.management' (errno: 150) (details...)

i'm having above error returned when try create many many table

trying create many many table between employees , supervisors, not error returned when make supervisor , employee tables. when go create management table above error.

these create table statements

employee table

create table if not exists employee (      emp_id int(4) not null,     yr_ser int(4),     status varchar(30),     emp_name varchar(30),     emp_gen varchar(1),     primary key (emp_id) ); 

supervisor table

create table if not exists supervisor (     sup_id int(4) not null,     sup_name varchar(30) not null,     gen int(4),     dep_id int(4),      primary key (sup_id),     index (dep_id),      foreign key (dep_id)         references department(dep_id)         on update cascade on delete restrict     ); 

but when go create table error

management table

create table if not exists management (     emp_id int(4) not null,     sup_id int(4) not null,      primary key (emp_id, sup_id),     index (emp_id),     index (sup_id),      foreign key (emp_id)         references employee(emp_id)         on update cascade on delete restrict,      foreign key (sup_id)         references supervisor(act_id)         on update cascade on delete restrict ); 

help appreciated, thank you.

your may-to-many table references field act_id in supervisor table, no such field defined. should sup_id instead:

create table if not exists management ( emp_id int(4) not null, sup_id int(4) not null,  primary key (emp_id, sup_id), index (emp_id), index (sup_id),  foreign key (emp_id)     references employee(emp_id)     on update cascade on delete restrict,  foreign key (sup_id)     references supervisor(sup_id) -- here     on update cascade on delete restrict );