SQL Query选择'Next'记录(类似于First或Top N)

Question

如果某个记录不存在,我需要进行查询以返回下一个(或上一个)记录.例如,请考虑下表:

ID (primary key)    value
1                    John
3                    Bob
9                    Mike
10                   Tom.

如果7不存在,我想查询id为7或更大的记录.

我的问题是,

1. 这些类型的查询是否可以使用SQL？
2. 在DB世界中调用了哪些这样的查询？

谢谢!

Answer 1

是的,这是可能的,但实现将取决于您的RDBMS.

这是它在MySQL,PostgreSQL和SQLite中的样子:

select ID, value
from YourTable
where id >= 7
order by id
limit 1

在MS SQL-Server,Sybase和MS-Access中:

select top 1 ID, value
from YourTable
where id >= 7
order by id

在Oracle中:

select * from (
    select ID, value
    from YourTable
    where id >= 7 
    order by id
)
where rownum = 1

在Firebird和Informix中:

select first 1 ID, value
from YourTable
where id >= 7
order by id

在DB/2中(此语法在SQL-2008标准中):

select id, value
from YourTable
where id >= 7
order by id
fetch first 1 rows only

在那些具有"窗口"功能的RDBMS中(在SQL-2003标准中):

select ID, Value
from (
  select 
    ROW_NUMBER() OVER (ORDER BY id) as rownumber,
    Id, Value
  from YourTable
  where id >= 7
) as tmp                  --- remove the "as" for Oracle
where rownumber = 1

如果您不确定您拥有哪种RDBMS:

select ID, value
from YourTable
where id = 
      ( select min(id)
        from YourTable
        where id >= 7
      )