Question

我正在尝试在row_number中使用变量顺序，当每个案例都有一个没有asc或desc定义的单个列时，它会起作用。但是当我定义多个列或使用asc或desc时它不起作用。

这有效：

select top(@perpage) *,row_number()
 over (order by
case @orderby when 'updated' then date_edited
              when 'oldest' then date_added  
  end
) 
as rid from
(select * from ads) a
 where rid>=@start and rid<@start+@perpage

但我想这样做：

select top(@perpage) *,row_number()
 over (order by
case @orderby when 'updated' then date_edited, user_type desc
              when 'oldest' then date_added, user_type desc
              when 'newest' then date_added desc, user_type desc
              when 'mostexpensive' then price desc, user_type desc
              when 'cheapest' then pricedesc, user_type desc
              when '' then user_type desc
  end
) 
as rid from
(select * from ads) a
 where rid>=@start and rid<@start+@perpage

Answer 1

请改为尝试：

select top(@perpage) *,row_number()
 over (order by
case @orderby when 'updated' then date_edited
              when 'oldest' then date_added
end,
case @orderby when 'newest' then date_added
end desc,
case @orderby when 'mostexpensive' then -price
              when 'cheapest' then pricedesc

end, 
  user_type desc
) 
as rid from ads a
where rid>=@start and rid<@start+@perpage

Answer 2

试试这个

select top(@perpage) *,row_number()
 over (order by
case @orderby when 'updated' then date_edited end,
case @orderby when 'oldest' then date_added end,
case @orderby when 'newest' then date_added end desc,
case @orderby when 'mostexpensive' then price end desc,
case @orderby when 'cheapest' then price end,
user_type desc
) 
as rid from
(select * from ads) a
 where rid>=@start and rid<@start+@perpage

Answer 3

CASE是一个返回单个值的表达式。由于第二个排序列始终相同，因此您可以：

 over (order by
case @orderby when 'updated' then date_edited
              when 'oldest' then date_added
              when 'newest' then date_added desc
              when 'mostexpensive' then price desc
              when 'cheapest' then pricedesc
  end, user_type desc
)

（当@orderby等于''时，case表达式将为每一行生成NULL - 但由于所有NULL排序在一起，这很好）

注意到并非所有的列名称都提供了兼容的类型 - 在这种情况下，这可能会更好：

 over (order by
case @orderby when 'updated' then date_edited
              when 'oldest' then date_added
  end,
  case @orderby 
        when 'newest' then date_added
  end desc,
  case @orderby
        when 'mostexpensive' then price
  end desc,
  case @orderby
        when 'cheapest' then price
  end asc,
  user_type desc
)

对于每种数据类型和所需的asc / desc组合，您可以有一个单独的CASE语句 - 如上所述，每个语句只会为任何NULL值生成@orderby个提及。

sql server：在row_number（）中使用变量顺序

3 个答案: