hi,
I am new to mysql but have experience on oracle and am implemnting a web db solution with mysql.

I create two tables

Cities which has 2 fields

citycode mediumint primary key
cityname varchar(20)

and

pincodes

pincode mediumint primary key
areaname varchar(20)
citycode mediumint references cities (citycode )
match full

the not null constraint is specified for the primary and foreign key fields .

My problem is even after doing this the pincodes table
is allowing entries for citycodes not in the cities master
table .

where am i going wrong or are there any other constraints
needed to implement this.

bye