I have a look as relationship between Parent Object and Child Object.
I am creating Child Object record first and creating the Parent Object record later using custom detail button on Child Object. So on the click of button on Child Object I am redirecting it to Parent Object record with some values pre populating from child object record to parent object record using url hack.
So after saving the parent object record I want the lookup field on child object to populate with parent object record Id.
Please explain to me how to update the lookup field (look up to parent record) on the child object record with parent object record id.