您可以使用ROW_NUMBER()函数在每个搜索结果中为每个搜索结果项指定一个排名:
SELECT SearchResultItemID,
SearchResultID,
Name,
Value,
RowNumber = ROW_NUMBER() OVER(PARTITION BY SearchResultID ORDER BY SearchresultItemID)
FROM SearchResultItem;
如果您知道项目数量,则可以使用聚合函数来获取每个名称/值对:
WITH RankedItem AS
( SELECT SearchResultItemID,
SearchResultID,
Name,
Value,
RowNumber = ROW_NUMBER() OVER(PARTITION BY SearchResultID ORDER BY SearchresultItemID)
FROM SearchResultItem
)
SELECT SearchResultID,
Name1 = MIN(CASE WHEN RowNumber = 1 THEN Name END),
Value1 = MIN(CASE WHEN RowNumber = 1 then Value END),
Name2 = MIN(CASE WHEN RowNumber = 2 THEN Name END),
Value2 = MIN(CASE WHEN RowNumber = 2 then Value END),
Name3 = MIN(CASE WHEN RowNumber = 3 THEN Name END),
Value3 = MIN(CASE WHEN RowNumber = 3 then Value END),
Name4 = MIN(CASE WHEN RowNumber = 4 THEN Name END),
Value5 = MIN(CASE WHEN RowNumber = 4 then Value END)
FROM RankedItem
GROUP BY SearchResultID;
然后,您可以将其加入到您的搜索结果表中,提供完整的查询:
WITH RankedItem AS
( SELECT SearchResultItemID,
SearchResultID,
Name,
Value,
RowNumber = ROW_NUMBER() OVER(PARTITION BY SearchResultID ORDER BY SearchresultItemID)
FROM SearchResultItem
), Items AS
( SELECT SearchResultID,
Name1 = MIN(CASE WHEN RowNumber = 1 THEN Name END),
Value1 = MIN(CASE WHEN RowNumber = 1 then Value END),
Name2 = MIN(CASE WHEN RowNumber = 2 THEN Name END),
Value2 = MIN(CASE WHEN RowNumber = 2 then Value END),
Name3 = MIN(CASE WHEN RowNumber = 3 THEN Name END),
Value3 = MIN(CASE WHEN RowNumber = 3 then Value END),
Name4 = MIN(CASE WHEN RowNumber = 4 THEN Name END),
Value4 = MIN(CASE WHEN RowNumber = 4 then Value END)
FROM RankedItem
GROUP BY SearchResultID
)
SELECT SearchResult.SearchResultID,
SearchResult.ProductID,
SearchResult.SearchQuery,
SearchResult.WebsiteName,
SearchResult.URL,
SearchResult.IsFound,
SearchResult.CreatedOn,
SearchResult.BatchID,
SearchResult.Name,
Items.Name1,
Items.Value1,
Items.Name2,
Items.Value2,
Items.Name3,
Items.Value3,
Items.Name4,
Items.Value4
FROM SearchResult
INNER JOIN Items
ON SearchResult.SearchResultID = Items.SearchResultID;
SQL Fiddle 示例
如果要返回可变数量的值,则需要使用动态 SQL:
DECLARE @SQL NVARCHAR(MAX) = '';
SELECT @SQL = @SQL + ',[Name' + rn + '], [Value' + rn + '] '
FROM ( SELECT DISTINCT
rn = CAST(ROW_NUMBER() OVER(PARTITION BY SearchResultID ORDER BY SearchresultItemID) AS VARCHAR)
FROM SearchResultItem
) p;
SET @SQL = 'WITH RankedItem AS
( SELECT SearchResultItemID,
SearchResultID,
Name,
Value,
RowNumber = ROW_NUMBER() OVER(PARTITION BY SearchResultID ORDER BY SearchresultItemID)
FROM SearchResultItem
), UnPivoted AS
( SELECT upvt.SearchResultID,
Name = upvt.n + CAST(RowNumber AS VARCHAR),
upvt.v
FROM RankedItem
UNPIVOT
( n
FOR v IN ([Name], [Value])
) upvt
), Pivoted AS
( SELECT *
FROM UnPivoted
PIVOT
( MAX(V)
FOR Name IN (' + STUFF(@SQL, 1, 1, '') + ')
) pvt
)
SELECT SearchResult.SearchResultID,
SearchResult.ProductID,
SearchResult.SearchQuery,
SearchResult.WebsiteName,
SearchResult.URL,
SearchResult.IsFound,
SearchResult.CreatedOn,
SearchResult.BatchID,
SearchResult.Name' + @SQL + '
FROM SearchResult
INNER JOIN Pivoted
ON SearchResult.SearchResultID = Pivoted.SearchResultID;';
EXECUTE SP_EXECUTESQL @SQL;
SQL Fiddle 示例
注意我故意在动态 sql 中使用了一种不同的方法来执行此操作,只是为了表明有不止一种方法可以实现组合行的结果。