Re: must I create the function check_primary_key ?

On Wed, 25 Apr 2001, Peter J. Schoenster wrote:

> 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,
> 	type varchar (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');

You probably just want to use a REFERENCES constraint
employer_id int4 REFERENCES employer_profile(employer_id)

You'll need to have a primary key or unique constraint
on employer_profile(employer_id).  The references constraint
will also prevent you from deleting a employer_id
row that is being referenced.