如何限制起始值来自mysql中的其他表

Question

我有以下我的sql查询，我想从其他表中取出限制开始索引，我该怎么办？

SELECT std.totalmarks 
    FROM student as std 
    WHERE std.status=1 
ORDER BY (std.datetime) ASC 
    LIMIT ( 
      SELECT us.startnum 
      FROM user AS us 
      WHERE us.username='abc' 
     ),10 

Answer 1

select q.totalmarks from 
(
SELECT *,@curRow := @curRow + 1 AS row_number 
FROM student as std JOIN (SELECT @curRow := 0) r 
WHERE std.status=1 
ORDER BY (std.datetime) ASC 
) q 
where row_number>( 
      SELECT us.startnum 
      FROM user AS us 
      WHERE us.username='abc' 
     ) 
limit 10 

Answer 2

select * from 
    (SELECT std.totalmarks, numstart.startnum, @n:=@n+1 as number 
    FROM student as std, 
     (SELECT us.startnum 
      FROM user AS us 
      WHERE us.username='abc') as numstart, 
     (SELECT @n:=0) sess_var 
    WHERE std.status=1 
    ORDER BY (std.datetime) ASC) res 
where number>=startnum 
LIMIT 0,10