我试图将一个人的前三行的值全部显示在一行中。
我的数据如下：
id co_number client_no Client_name taken_date taken_value
--------------------------------------------------------------------------
270103 12 1111 John Doe 6/7/11 8:45 AM 108
270100 12 1111 John Doe 5/3/11 10:49 AM 109
270097 12 1111 John Doe 4/4/11 1:58 PM 109
270094 12 1111 John Doe 3/1/11 9:04 AM 106
270091 12 1111 John Doe 2/1/11 8:47 AM 105
270088 12 1111 John Doe 1/4/11 9:10 AM 106
270120 12 2222 Jane Smith 6/7/11 9:06 AM 215
270117 12 2222 Jane Smith 5/3/11 2:01 PM 216
270114 12 2222 Jane Smith 4/4/11 2:08 PM 214
270111 12 2222 Jane Smith 3/1/11 9:27 AM 209
270159 12 3333 John Adams 6/7/11 9:45 AM 205
270156 12 3333 John Adams 5/3/11 2:12 PM 203
270153 12 3333 John Adams 4/4/11 1:42 PM 202
270150 12 3333 John Adams 3/1/11 10:32 AM 198
我希望数据显示如下（Date1是最新的，然后是Date2，然后是Date3）：
co# Name Date1 Value1 Date2 Value2 Date3 Value3
-------------------------------------------------------------------------------------------
12 John Doe 2011-06-07 08:45 108.0 2011-05-03 10:49 109.0 2011-04-04 13:58 109.0
这是我到目前为止所拥有的。它工作但速度慢（返回一个co_number需要30秒）所以我想知道是否有更好的方法来做到这一点。
select
vmain.co_nmber, vmain.Client_name, vmain.Taken_date, vmain.Taken_value
, (select top 1 Taken_date from vital vdate where vdate.co_nmber=vmain.co_nmber and vdate.Medical_Record_Number=vmain.Medical_Record_Number and vdate.Taken_date < vmain.Taken_date order by vdate.Taken_date desc) as date2
, (select top 1 Taken_value from vital v_value where v_value.co_nmber=vmain.co_nmber and v_value.Medical_Record_Number=vmain.Medical_Record_Number and v_value.Taken_date < vmain.Taken_date order by v_value.Taken_date desc) as value2
, (select top 1 Taken_date from vital vdate where vdate.co_nmber=vmain.co_nmber and vdate.Medical_Record_Number=vmain.Medical_Record_Number and vdate.Taken_date < (select top 1 Taken_date from vital vdate where vdate.co_nmber=vmain.co_nmber and vdate.Medical_Record_Number=vmain.Medical_Record_Number and vdate.Taken_date < vmain.Taken_date order by vdate.Taken_date desc) order by vdate.Taken_date desc) as date3
, (select top 1 Taken_value from vital vvalue where vvalue.co_nmber=vmain.co_nmber and vvalue.Medical_Record_Number=vmain.Medical_Record_Number and vvalue.Taken_date < (select top 1 Taken_date from vital vdate where vdate.co_nmber=vmain.co_nmber and vdate.Medical_Record_Number=vmain.Medical_Record_Number and vdate.Taken_date < vmain.Taken_date order by vdate.Taken_date desc) order by vvalue.Taken_date desc) as value3
from vital as vmain
inner join(
SELECT v.co_nmber, v.Medical_Record_Number, max(v.Taken_date) as Taken_date
FROM Vital v
and v.co_nmber = 12
GROUP BY v.co_nmber, v.Medical_Record_Number
) as vsub on vsub.co_nmber=vmain.co_nmber and vsub.Medical_Record_Number=vmain.Medical_Record_Number and vsub.Taken_date = vmain.Taken_date
and vmain.co_nmber = 12
order by vmain.co_nmber, vmain.Medical_Record_Number, vmain.Taken_date
帮助表示赞赏。
答案 0 :(得分：1)
最大的问题是“导致查询运行缓慢的原因是什么？”
您的表格是否正确编入索引？
也许你可以一次删除一个计算列，看看效果如何表现。
答案 1 :(得分：1)
您可以使用row_number为每个co和客户端编号记录。 在此之后，您可以选择第一个，然后左连接第二个和第三个。 应该更快。
with cVital as (
select v.co_nmber, v.Medical_Record_Number, v.Client_name,
v.taken_date, v.taken_value,
n = row_number() over (partition by v.co_nmber, v.Medical_Record_Number order by v.taken_date desc)
from Vital v
)
select [co#]=v1.co_nmber, [Name]=v1.Client_name,
Date1 = v1.taken_date, Value1 = v1.taken_value,
Date2 = v3.taken_date, Value2 = v2.taken_value,
Date3 = v2.taken_date, Value3 = v3.taken_value
from cVital v1
left join cVital v2
on v2.co_nmber = v1.co_nmber
and v2.Medical_Record_Number = v1.Medical_Record_Number
and v2.n = 2
left join cVital v3
on v3.co_nmber = v1.co_nmber
and v3.Medical_Record_Number = v1.Medical_Record_Number
and v3.n = 3
where v1.n = 1
order by v1.co_nmber, v1.Medical_Record_Number;
答案 2 :(得分：0)
好的，我更新了我的答案。这是一个基于我之前的查询工作的解决方案：
DECLARE @Name VARCHAR(100)
DECLARE @TmpName VARCHAR(100)
DECLARE @ID INT
DECLARE @CoNum INT
DECLARE @Date1 DATETIME
DECLARE @Date2 DATETIME
DECLARE @Date3 DATETIME
DECLARE @Value1 INT
DECLARE @Value2 INT
DECLARE @Value3 INT
DECLARE @IndexValue INT
DECLARE @SetValue INT
DECLARE @SetDate DATETIME
CREATE TABLE #OutputTable (
co_number INT,
Client_Name VARCHAR(200),
Date1 DATETIME,
Value1 INT,
Date2 DATETIME,
Value2 INT,
Date3 DATETIME,
Value3 INT
)
SELECT DISTINCT Client_name INTO #TempVitalNames FROM vital ORDER BY Client_name
WHILE (SELECT COUNT(*) FROM #TempVitalNames) > 0
BEGIN
SELECT @IndexValue = 0
SELECT TOP(1) @TmpName = Client_name FROM #TempVitalNames
SELECT TOP(3) * INTO #TempVital FROM vital WHERE Client_name = @TmpName ORDER BY taken_date DESC
WHILE (@IndexValue < 3)
BEGIN
SET @Name = (SELECT TOP 1 Client_name FROM #TempVital)
SET @CoNum = (SELECT TOP 1 co_number FROM #TempVital)
SELECT TOP 1 @ID = id FROM #TempVital
SET @SetDate = (SELECT TOP 1 taken_date FROM #TempVital)
SET @SetValue = (SELECT TOP 1 taken_value FROM #TempVital)
DELETE FROM #TempVital WHERE id = @ID
SET @Date1 = CASE WHEN @IndexValue = 0 THEN @SetDate ELSE @Date1 END
SET @Date2 = CASE WHEN @IndexValue = 1 THEN @SetDate ELSE @Date2 END
SET @Date3 = CASE WHEN @IndexValue = 2 THEN @SetDate ELSE @Date3 END
SET @Value1 = CASE WHEN @IndexValue = 0 THEN @SetValue ELSE @Value1 END
SET @Value2 = CASE WHEN @IndexValue = 1 THEN @SetValue ELSE @Value2 END
SET @Value3 = CASE WHEN @IndexValue = 2 THEN @SetValue ELSE @Value3 END
SELECT @IndexValue = @IndexValue + 1
END
INSERT INTO #OutputTable (co_number, Client_Name, Date1, Value1, Date2, Value2, Date3, Value3)
( SELECT @CoNum, @Name, @Date1, @Value1, @Date2, @Value2, @Date3, @Value3 )
DELETE #TempVitalNames WHERE Client_name = @TmpName
DROP TABlE #TempVital
END
DROP TABLE #TempVitalNames
SELECT * FROM #OutputTable
DROP TABLE #OutputTable
好克劳迪娅。这将首先将表中的所有唯一名称拉入临时表。然后它将遍历每个名称。在迭代循环中，它将执行我的上一个程序将执行的操作，并从前3个名称中提取所需日期，并将它们插入另一个临时表中。处理完所有名称后，它将转储临时表的内容，该表应该是您要查找的输出。我使用您提供的测试数据在我的系统上运行此查询，并在1秒内执行。我知道你可能有更多行，然后我必须使用，但它似乎工作得很好。如果您还有其他需要，请告诉我，我会相应修改。如果需要，您可以随意向SELECT语句添加任何类型的where子句。您可能还需要更改某些数据类型。我不确定你的taken_value是整数还是小数或其他什么。我选择了INT，但您可以根据自己的需要进行更改。
答案 3 :(得分：0)
缓慢可能是在Select语句中使用相关子查询。请记住，子查询将对表中的每条记录执行
如果您只使用Temp表（或Table变量）返回固定数量的值，并且Row_Number（）Over方法将起作用：
SELECT ROW_NUMBER() OVER (PARTITION BY TheKey ORDER BY DateValue DESC) RowNum, TheKey, DateValue, OtherValue INTO tmp FROM SomeTable WHERE .....
SELECT x1.TheKey, x1.DateValue date1, x1.OtherValue Value1, x2.DateValue Date2, x2.OtherValue Value2, x3.CreateDate Date3, x3.OtherValue Value3
FROM (SELECT * FROM #tmp WHERE rownum=1) x1
left JOIN (SELECT * FROM #tmp WHERE rownum=2) x2 ON x1.TheKey = x2.TheKey
left JOIN (SELECT * FROM #tmp WHERE rownum=3) x3 ON x1.TheKey = x3.TheKey