SQL：即使没有匹配项，也返回一些值

我有一个sql查询，我在其中传递学生ID“in”子句。 如果没有与给定id匹配的记录，则不会返回任何内容。 我希望查询返回false或notexist等内容，即使没有记录匹配

//伪查询（为了简洁起见，我限制查询一个表，实际查询涉及其他表。）

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应用

或为空

Select s.student_id 
from STUDENTS   s
WHERE s.student_id in (?,?,?)
  or s.student_id is null;

如果要连接，请使用左连接：

select s.student_id
from students s
left join othertable o
  on o.something = s.something
WHERE s.student_id in (?,?,?)
  or s.student_id is null;

如果学生在右边：

select s.student_id
from othertable o
left join students s
  on o.something = s.something
  and s.student_id in (?,?,?) -- we put this into the join clause so we don't need the "or is null"
;

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学生是否有表格多行或大数据？

select s.student_id
from othertable o
left join students s
  on o.something = s.something
  and s.student_id in (?,?,?) -- we put this into the join clause so we don't need the "or is null"
;

IF EXISTs(Select student_id from STUDENTS  WHERE s.student_id in (?,?,?))
  BEGIN 
    Select student_id from STUDENTS  WHERE s.student_id in (?,?,?)
 END
  ELSE 
    select 0