mysql - 如何在sql查询中放入条件

Question

如果“flag”列等于“shown”，我想在分数表中显示所有得分记录，在学生表中显示学生姓名。否则，如果 Score 表中的“flag”列等于“hidden”，我将显示学生姓名 =“Student”的所有得分记录。最后按时间顺序显示所有内容。

这是我尝试过的:

select s.student_name if h.flag = 'shown', select 'student' as s.student_name if h.flag = 'hidden',
   h.subject1_score,
   h.subject2_score,
   h.subject3_score,
   h.subject4_score,
   h.subject5_score,
   h.exam_date
from Score_Table h
join Student s on h.student_id = u.student_id
order by h.exam_date 

但这似乎行不通。我应该改变什么？谢谢!

Answer 1

您的 IF 语法已关闭。阅读http://dev.mysql.com/doc/refman/5.7/en/control-flow-functions.html

select if(h.flag = 'shown',s.student_name,'student') student_name,
   h.subject1_score,
   h.subject2_score,
   h.subject3_score,
   h.subject4_score,
   h.subject5_score,
   h.exam_date
from Score_Table h
join Student s on h.student_id = s.student_id
order by h.exam_date