Cascade Delete Query

I have three tables. Product, Company, Employee

ProductId of Product table is foregin key for Company and CompanyId of Company table is foregin key for Employee

So on deleting ProductId from Product table, all the related records in other tables should delete. But I can't touch schema(can't use a开发者_运维问答lter table). How should I write the query in that case..

If you can't add constraints that propagates the delete, you have to write all the necessary deletes yourself:

delete employee where companyid in (select companyid from company c where productid = xxx);
delete company where productid=xxx;
delete product where productid=xxx;

Try this option. I don't have environment to test this. I guess with some changes it should work at your end.

DELETE Product,Company,Employee 
FROM 
user LEFT JOIN items ON product.productid = company.productid 
LEFT JOIN orders ON company.productid = product.productid 
WHERE product.productid = [$productid]