如何将字符串字段类似SUM输出?

|------------------|-----------------|
|article_title     | article_author|
|------------------|---------------|
|部门变量测试01 | zhang_gl  |
|------------------|---------------|
|部门变量测试01 |                   |
|----------------- |---------------|
|部门变量测试01| xlzhang,Jacks |
|------------------|---------------|

DECLARE @str VARCHAR(8000)
SET @str = ''
SELECT @str = @str + ',' + article_author
FROM outcome_article
WHERE (article_title = '部门变量测试01') and len(article_author) > 0

SET @Article_Author = right(@Article_Author len(@Article_Author) -1)

查询结果：zhang_gl,xlzhang,Jacks