在LINQ中表示Oracle LISTAGG（）功能？

Question

考慮下面的PL/SQL查詢：

SELECT department_id, LISTAGG(last_name, '; ') 
    WITHIN GROUP (ORDER BY last_name) "Emp_list" 
FROM employees 
GROUP BY department_id; 

將是LINQ相當於上面的？ 謝謝！

Answer 1

編輯：既然你想要其他列，並希望分組，你不能使用我原來建議的方法。這裏有一個新的解決方案，但生成的SQL是不完全的偉大：

from employee in employees 
group employee by employee.department_id into grpEmployee 
select new { 
    DepartmentId = grpEmployee.Key, 
    LastNames = string.Join(", ", employees.Where(e => e.department_id == grpEmployee.Key) 
            .OrderBy(e => e.last_name).Select(e => e.last_name)) 
} 

注意，此方法結合了查詢類和lambda語法。

---

這應該可以做到。我們選擇所有的姓氏，然後將其作爲最終結果加入單個字符串中。

string.Join("; ", (from employee in employees 
        where employee.department_id == 30 
        orderby employee.last_name 
        select employee.last_name))