总是返回记录SQL服务器

Question

指定数量的我有一个查询，我一直想为返回10个记录：

set rowcount 10 
select row_number() over(order by count(*) desc) row_num 
    ,hist_report_id 
    ,max(rpt_report_name) report_name 
from utility.dbo.tbl_report_history 
join utility.dbo.tbl_report_definitions 
    on hist_report_id = rpt_report_id 
where hist_user_id = 1038 
group by hist_report_id 

，如果我有10分或更多的记录，工作正常。问题是当记录少于10条时，我仍然需要在report_id和report_name字段中返回带有空值的rownumber字段。

如果只有7条记录返回，结果应该是这样的：

row_num report_id report_name 
1  id1  name1 
2  id2  name2 
3  id3  name3 
4  id4  name4 
5  id5  name5 
6  id6  name6 
7  id7  name7 
8  null  null 
9  null  null 
10  null  null 

有什么建议？

我使用SQL Server 2008的

Answer 1

绝不能count()回报小于零......所以很合理牛逼通过工会在数列与附加-110个空行

另外，不要使用SET ROWCOUNT，因为它影响中间结果

SELECT TOP 10 
    row_number() over(order by TheCount desc) AS row_num, 
    hist_report_id, 
    report_name 
FROM 
    (
    select 
     ,count(*) AS TheCount 
     ,hist_report_id 
     ,max(rpt_report_name) AS report_name 
    from 
     utility.dbo.tbl_report_history 
     join 
     utility.dbo.tbl_report_definitions on hist_report_id = rpt_report_id 
    where hist_user_id = 1038 
    group by hist_report_id 
    UNION ALL 
    SELECT TOP 10 
     -1, NULL, NULL 
    FROM sys.columns 
    ) T 

Answer 2

，我记得最简单的方法：

1. Insert的select result在#temptable
2. While count(*) < 10insert行into #temptable

Answer 3

你可以考虑使用一个TVF返回给你一组的，你可以用外连接数：

CREATE FUNCTION SetOfValues (@beginningAt int, @endingAt int, @step int = 1) 
RETURNS 
    @result TABLE (value int) 
AS BEGIN 
    declare @counter int set @counter = @beginningAt 
    while(@counter<=@endingAt) 
    begin 
     insert into @result values(@counter) 
     set @counter = @counter + @step 
    end 
RETURN 
END 
GO 

-- USAGE 
with cte as (
    select row_number() over (order by hist_report_Id) as row_num, 
    hist_report_Id, report_name 
    from tbl_report_history join tbl_report_definitions on hist_report_Id = rpt_reportId) 
select value, hist_reportId, report_name 
from dbo.SetOfValues(1,10,1) as t on t.value = cte.row_num 

Answer 4

with 
/* Create 10 dummy rows using recursion */ 
RowSequence as (
    select 0 Idx 
    union all 
    select RowSequence.Idx+1 Idx from RowSequence where RowSequence.Idx+1<10 
    ), 
/* Your Query */ 
YourQuery as(
    select row_number() over(order by count(*) desc) row_num 
     ,hist_report_id 
     ,max(rpt_report_name) report_name 
    from utility.dbo.tbl_report_history 
    join utility.dbo.tbl_report_definitions 
     on hist_report_id = rpt_report_id 
    where hist_user_id = 1038 
    group by hist_report_id 
    ) 
/* Now all together */ 
select top 10 * from (
    select * from YourQuery 
    union all 
    select null, null, null from RowSequence 
    ) a 
/* To avoid the recursion maximum level 100 */ 
option (maxrecursion 0)