How to collect MySQL base path using JPQL?

How to collect MySQL base path using JPQL?

I am trying to make a simple Java application on windows-7 that can
database backup from mysql. I need mysql base path . I tried using JPQL
that is
EntityManagerFactory emf =
Persistence.createEntityManagerFactory("BackupRestoreMysqlDatabasePU");
EntityManager em = emf.createEntityManager();
String path = em.createQuery("SELECT
@@basedir").getSingleResult().toString();
System.out.println("My Database Path::" + path);
When I run it, show following error:
Exception in thread "main" java.lang.IllegalArgumentException: An
exception occurred while creating a query in EntityManager:
Exception Description: Syntax error parsing [SELECT @@basedir].
[16, 16] A select statement must have a FROM clause.
[7, 16] The identification variable '@@basedir' is not following the
rules for a Java identifier.
at
org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1585)
atJava Result: 1
Please help me.