must I create the function check_primary_key ?

Hi,

Thanks to many who clued me on on using "arrow keys" to 
traverse history. I just installed readline and 7.1 .. seems that 
mysql has its own readline.

I want to use this referential integrity etc. that I've never used in 
mysql ... so I tried many things and looked here and there ... My 
example below produces this error:

> CreateTrigger: function check_primary_key() does not exist

Here is what I was trying to create:

DROP TABLE company_profile;

CREATE TABLE company_profile (employer_id int4,    leadership text,company_description  text,key_financial_statictics
varchar(255),company_name varchar (255),url varchar (255),sec_fillings_url varchar (255),mission text,employees
int4,typevarchar (50),growth_rate varchar (50),culture  text,year int4,PRIMARY KEY (employer_id)
 
);

CREATE TRIGGER employer_id_exists
BEFORE INSERT OR UPDATE ON company_profile FOR EACH 
ROW
EXECUTE PROCEDURE check_primary_key('employer_id', 
'employer_profile', 'employer_id');

__end example

I just copied the above TRIGGER  .... but it doesn't work for me.

Thanks,

Peter
All idioms must be learned.
Good idioms only need to be learned once. 
--Alan Cooper