本文的内容并不能完全回答问题，但它会建议您如何正确规范表格以简化问题.

The content of this doesn't totally answers the question but it will suggest on how you can properly normalize the table in order for theproblem to be simplified.

这是一个多对多关系.

Employees
- ID (Primary Key)
- Name
- Type

Task
- ID (Primary Key)
- Name

Work
- EmployeeID (Foreign Key)
- TaskID (Foreign Key)

员工表

id         name        type
 1         john         2
 2         peter        1
 3         leah         2
 4         frank        1
 5         tang         3

任务表

 id         name        
  1         task1       
  2         task2       
  3         task3       
  4         task4  

工作台

TaskID  EmployeeID
1           1
1           3
2           2
2           4
3           1
3           2
3           3
4           4

查询，

SELECT  t.ID, t.Name,
        STUFF(
        (SELECT ',' + b.Name
        FROM    Work a
                INNER JOIN Employee b
                    ON a.EmployeeID = b.ID
        WHERE   a.TaskID = t.ID 
        FOR XML PATH (''))
        , 1, 1, '')  AS NamesList
FROM    Task t
-- WHERE    ..... -- add additional conditions...
GROUP   BY t.ID, t.Name

• SQLFiddle 演示