How to refer to child of a child module in Maven

I have following module structure.

  Project 
     -- datamodel
     -- server
          |---- ear
           ---- api       

If I modify something in datamodel.I would like to only execute pom for datamodel.However 'ear' module is doing the final packaging.So, I end up executing datamodel and ear. I tried following command, but did not work.

 mvn install -pl datamodel,server:e开发者_开发问答ar.

How to refer to the child module of a child module? I assume that whatever we are specifying after "-pl" are the artifactIds of the module that we want to execute.

Refer to the groupId:artifactId not the folder name.