I have Two custom  Object Account And Opportunity 
Account :Parent
Opportunity:Chlid
on the parent object, I have a checkbox:Request,
On the child object, I have a Picklist: Model,Completed,runnig
In opportunity  Selected the Piclist Value Model And Running When Parent Account Checkbox is True otherwise Select Picklist Value Runnng When Parent Account Checkbox is False
how  to write a Apex Trigger Code

thanks in advance 

I have Two custom  Object Account And Opportunity 

Account :Parent

Opportunity:Chlid
on the parent object, I have a checkbox:Request,
On the child object, I have a Picklist: Model,Completed,runnig
In opportunity  Selected the Piclist Value Model And Running When Parent Account Checkbox is True otherwise Select Picklist Value Runnng When Parent Account Checkbox is False

how  to write a Apex Trigger Code

 

I have Two custom  Object Account And Opportunity 
Account :Parent
Opportunity:Chlid
on the parent object, I have a checkbox:Request,
On the child object, I have a Picklist: Model,Completed,runnig
In opportunity  Selected the Piclist Value Model And Running When Parent Account Checkbox is True otherwise Select Picklist Value Runnng When Parent Account Checkbox is False
how  to write a Apex Trigger Code

thanks in advance