先上图：
- SQL code
ORDER BY CASE when @P_SORTEXPRESSION = 'COURSE_DESC' THEN COURSE_DESC,T.USER_GRADE, T.USER_GRADE_LEVEL, T.DIFFICULTY_LEVEL end, CASE when @P_SORTEXPRESSION = 'COURSE_DESC DESC' THEN COURSE_DESC DESC, T.USER_GRADE, T.USER_GRADE_LEVEL, T.DIFFICULTY_LEVEL END, CASE WHEN @P_SORTEXPRESSION = 'USER_GRADE' THEN USER_GRADE, T.COURSE_DESC, T.USER_GRADE_LEVEL, T.DIFFICULTY_LEVEL END, CASE WHEN @P_SORTEXPRESSION = 'USER_GRADE DESC' THEN USER_GRADE DESC, T.COURSE_DESC, T.USER_GRADE_LEVEL, T.DIFFICULTY_LEVEL END, CASE WHEN @P_SORTEXPRESSION = 'USER_GRADE_LEVEL' THEN USER_GRADE_LEVEL, T.COURSE_DESC, T.USER_GRADE, T.DIFFICULTY_LEVEL END, CASE WHEN @P_SORTEXPRESSION = 'USER_GRADE_LEVEL DESC' THEN USER_GRADE_LEVEL DESC, T.COURSE_DESC, T.USER_GRADE, T.DIFFICULTY_LEVEL END
相信大家都看懂我想干嘛了，对，排序，但是这个Case Then后面是不是只能跟一个值？那要想实现我想要的这种结果该如何操作？！
------解决方案--------------------
你这个需要使用判断语句,然后去执行.
例如:
if @P_SORTEXPRESSION = 'COURSE_DESC'
select .... from ... order by OURSE_DESC,T.USER_GRADE,T.USER_GRADE_LEVEL,T.DIFFICULTY_LEVEL
else
if @P_SORTEXPRESSION = 'COURSE_DESC DESC'
select .... from ... order by OURSE_DESC DESC, T.USER_GRADE,T.USER_GRADE_LEVEL,T.DIFFICULTY_LEVEL
....