我有我正在执行的hql查询，但是收到了一个错误，我并不真正了解其原因。
这是我的密码：

@Override
public List<StaffRequest> getStaffLeaveRequest(String userID, Date startDate, Date endDate) 
{
    Session currentSession = sessionFactory.getCurrentSession();        

    List<StaffRequest> results = 
    currentSession.createQuery("select new com.timesheet_Webservice.CustomEntity.StaffRequest(lr.leave_ID, lr.leave_Employee, concat(s.staff_First_Name, ' ', s.staff_Last_Name), "
            + "(lr.leave_Days*8.5), lr.leave_Comments, '1805', concat(pro.project_Pastel_Prefix, ' - ', pro.project_Description), lr.leave_Start, lr.leave_End, lr.leave_IsApproved, "
            + "(select lt.leaveType_Description from LeaveType lt where lt.leaveType_ID = lr.leave_Type)) "
            + "from Staff s, Project pro, Leave lr "
            + "where lr.leave_Employee = s.staff_Code and pro.project_Code = 1805 and lr.leave_Approved = :userID and lr.leave_IsApproved = 0 and s.staff_IsEmployee <> 0 "
            + "and lr.leave_Start between :startDate and :endDate "
            + "order by concat(s.staff_First_Name, ' ', s.staff_Last_Name)")
            .setParameter("userID",userID).setParameter("startDate", startDate).setParameter("endDate", endDate).getResultList();   

    return results;
}

我在尝试执行时在网页上出现以下错误：
org.hibernate.exception.sqlgrammareexception:无法提取结果集
还有这个控制台错误：
错误：您的sql语法有错误；请检查与您的mariadb服务器版本对应的手册，以了解在第1行的“leave2\ where leave2\ leave\ employee=staff0\ staff\ code and project1\ proj”附近使用的正确语法
这似乎表明where子句有些错误，但我看不出有什么特别的错误。
更新：实体类
项目

@Entity
@Table(name="project")
public class Project {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="Project_Code")
    public int project_Code;

    @Column(name="Project_Customer")
    public int project_Customer;

    //A lot more attributes...

}
工作人员

@Entity
@Table(name="staff")
public class Staff 
{
    @Id
    @Column(name="Staff_Code")
    public String staff_Code;
    ...
}