sql-subselect

I need to join a table to the a select/group-by query (which includes the same table), and I'd like to do it using Arel. I have a table of :phenotypes which are has_and_belongs_to_many :genes , which are themselves has_and_belongs_to_many :orthogroups . As a result, the relationship between phenotypes and orthogroups are many-to-many. I have two scopes (on Orthogroup) which get all orthogroups associated with a specific phenotype: scope :with_phenotype, lambda { |phenotype_id| where("observations.phenotype_id = ?", phenotype_id). joins("inner join orthologies on (orthologies.orthogroup_id =

I have two tables Employee and Department following are the entity classes for both of them Department.java @Entity @Table(name = "DEPARTMENT") public class Department { @Id @Column(name = "DEPARTMENT_ID") @GeneratedValue(strategy = GenerationType.AUTO) private Integer departmentId; @Column(name = "DEPARTMENT_NAME") private String departmentName; @Column(name = "LOCATION") private String location; @OneToMany(cascade = CascadeType.ALL, mappedBy = "department", orphanRemoval = true) @Fetch(FetchMode.SUBSELECT) //@Fetch(FetchMode.JOIN) private List<Employee> employees = new ArrayList<>(); }