如何在SQL中獲得UNION的前10名結果？

我目前在存儲過程中有下面的代碼（見下文）。爲了總共返回10個結果，我選出了每個聯盟的前五名。不過，我想參加聯盟的前10名，而不是每個人的5名。有任何想法嗎？這可能嗎？如何在SQL中獲得UNION的前10名結果？

BEGIN 
SELECT TOP 5 
    a_object_ID as [id], 
    a_object_name as [name], 
    'A_object' as [Type] 
FROM [database].[dbo].[table_a] 
WHERE a_object_name LIKE @Search + '%' 

UNION ALL 

SELECT TOP 5 
    b_object_ID as [id], 
    b_object_name as [name], 
    'B_object' as [Type] 
FROM [database].[dbo].[table_b] 
WHERE b_object_name LIKE @Search + '%' 

ORDER BY [name] 
END

來源

2011-05-09 WEFX

爲什麼這有linq-to-sql標記如果你想在SQL中做到這一點？ – BrokenGlass 2011-05-09 20:28:51

對不起@BrokenGlass，我刪除了標籤。 – WEFX 2011-05-09 20:29:57

這個怎麼樣？

SELECT TOP 10 * 
FROM 
(
SELECT a_object_ID as [id], 
    a_object_name as [name], 
    'A_object' as [Type] 
FROM [database].[dbo].[table_a] 
WHERE a_object_name LIKE @Search + '%' 
UNION ALL 
SELECT b_object_ID as [id], 
    b_object_name as [name], 
    'B_object' as [Type] 
FROM [database].[dbo].[table_b] 
WHERE b_object_name LIKE @Search + '%' 
) x 
ORDER BY [name]

來源

2011-05-09 20:31:49 AdaTheDev

是的，非常有可能。你只需要從聯合結果中選擇前10名。

SELECT TOP 10 * FROM (
    SELECT 
     a_object_ID as [id], 
     a_object_name as [name], 
     'A_object' as [Type] 
    FROM [database].[dbo].[table_a] 
    WHERE a_object_name LIKE @Search + '%' 

    UNION ALL 

    SELECT 
     b_object_ID as [id], 
     b_object_name as [name], 
     'B_object' as [Type] 
    FROM [database].[dbo].[table_b] 
    WHERE b_object_name LIKE @Search + '%' 
) u 
ORDER BY u.[name]

來源

2011-05-09 20:31:35 dotjoe

謝謝@dotjoe，我默認了@AdaTheDev，因爲他的回答是在你的之前。 – WEFX 2011-05-09 20:48:33

讓你UNION子查詢

SELECT TOP 10 * 
FROM (
    SELECT 
     a_object_ID as [id], 
     a_object_name as [name], 
     'A_object' as [Type] 
    FROM [database].[dbo].[table_a] 
    WHERE a_object_name LIKE @Search + '%' 

    UNION ALL 

    SELECT 
     b_object_ID as [id], 
     b_object_name as [name], 
     'B_object' as [Type] 
    FROM [database].[dbo].[table_b] 
    WHERE b_object_name LIKE @Search + '%' 
) AS subquery 
ORDER BY subquery.[name]

來源

2011-05-09 20:31:57

爲什麼查詢複雜化？這將做的工作：

set rowcount 10 

    SELECT a_object_ID as [id], 
     a_object_name as [name], 
     'A_object' as [Type] 
    FROM [database].[dbo].[table_a] 
    WHERE a_object_name LIKE @Search + '%' 
UNION ALL 
    SELECT b_object_ID as [id], 
     b_object_name as [name], 
     'B_object' as [Type] 
    FROM [database].[dbo].[table_b] 
    WHERE b_object_name LIKE @Search + '%' 
ORDER BY [name] 

set rowcount 0

來源

2011-05-09 20:44:50

以上答案都是浪費的子查詢收集，然後拒絕潛在的大量的行。你可以改善使用子查詢的問題。

declare @Recs int = 10; 

with cte1 as (
SELECT TOP (@Recs) 
    a_object_ID as [id], 
    a_object_name as [name], 
    'A_object' as [Type] 
FROM [database].[dbo].[table_a] 
WHERE a_object_name LIKE @Search + '%' 
) 
, cte2 as 
(
SELECT TOP (@Recs) 
    a_object_ID as [id], 
    a_object_name as [name], 
    'B_object' as [Type] 
FROM [database].[dbo].[table_a] 
WHERE a_object_name LIKE @Search + '%' 
) 
SELECT TOP (@Recs) [id], [name], [Type] 
(
select [id], [name], [Type] from cte1 
union all 
select [id], [name], [Type] from cte2 
) SQ 
ORDER BY [Name]

來源

2014-04-08 14:30:41 WaitForPete

如何在SQL中獲得UNION的前10名結果？

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