title: CrudRepository custom method implementation?
body: <p>I was reading about Crudrepository which is an interface for generic CRUD operations on a repository for a specific type.</p>
  
  <p>But we can create our custom interface and extend CrudRepository.</p>
  
  <p>I have looked at the example online and saw that they have not provided implentation anywhere.</p>
  
  <p><a href="https://github.com/netgloo/spring-boot-samples/blob/master/spring-boot-mysql-springdatajpa-hibernate/src/main/java/netgloo/models/UserDao.java#L16" rel="noreferrer">Sample:</a></p>
  
  <pre><code>@Transactional
  public interface UserDao extends CrudRepository&lt;User, Long&gt; {
  
    /**
     * Return the user having the passed email or null if no user is found.
     * 
     * @param email the user email.
     */
    public User findByEmail(String email);
  
  }
  </code></pre>
  
  <p>Does the argument have to be the same name as the column name or the method name like "findBy" + columnName?</p>