SQL单查询更新答案

【问题标题】：SQL single query updateSQL单查询更新
【发布时间】：2009-10-23 07:10:17
【问题描述】：

我不得不将值插入到我们数据库中的新列中，但我无法以一致的方式进行此操作。有很多数据，所以手动做任何事情几乎是不可能的。让我来设置舞台：

我们有一个名为 Occurrence 的表和一个名为 OccurenceBuckets 的表，其中每个事件都引用了它已分配到的存储桶。以前这是一个单向引用，但出于各种原因，我们决定将引用从 OccurrenceBucket 添加回第一个 Occurrence（即第一次出现）。现在的表格如下所示：

CREATE TABLE Occurrence
  OccurrenceID uniqueidentifier,
  OccurrenceBucketID uniqueidentifier,
  OccurrenceTime datetime,
  OccurrenceMessage nvarchar
  ...other meta data...

CREATE TABLE OccurrenceBucket
  OccurrenceBucketID uniqueidentifier,
  ...other meta data...
  FirstOccurrenceID uniqueidentifier,
  FirstOccurrenceTime datetime,
  FirstOccurrenceMessage nvarchar

我正在寻找一种方法来确定属于存储桶的第一次出现，并为我的所有出现桶分配 FirstOccurrenceID、FirstOccurrenceTime 和 FirstOccurrenceMessage 的值。

你们中的任何 sql-fu 专家有时间帮助我吗，我的所有尝试都被视为产生不正确或不完整的事件选择。

【问题讨论】：

标签： sql tsql sql-update

【解决方案1】：

你可以试试这个

DECLARE @Occurrence TABLE(
        OccurrenceID INT,
        OccurrenceBucketID INT,
        OccurrenceTime DATETIME,
        OccurrenceMessage VARCHAR(MAX)
)

INSERT INTO @Occurrence (OccurrenceID,OccurrenceBucketID,OccurrenceTime,OccurrenceMessage)  
SELECT 1, 1, '01 Jan 2009', 'A'
INSERT INTO @Occurrence (OccurrenceID,OccurrenceBucketID,OccurrenceTime,OccurrenceMessage)  
SELECT 2, 1, '02 Jan 2009', 'B'
INSERT INTO @Occurrence (OccurrenceID,OccurrenceBucketID,OccurrenceTime,OccurrenceMessage)  
SELECT 3, 1, '03 Jan 2009', 'C'


INSERT INTO @Occurrence (OccurrenceID,OccurrenceBucketID,OccurrenceTime,OccurrenceMessage)  
SELECT 4, 2, '04 Jan 2009', 'D'
INSERT INTO @Occurrence (OccurrenceID,OccurrenceBucketID,OccurrenceTime,OccurrenceMessage)  
SELECT 5, 2, '05 Jan 2009', 'E'
INSERT INTO @Occurrence (OccurrenceID,OccurrenceBucketID,OccurrenceTime,OccurrenceMessage)  
SELECT 6, 2, '06 Jan 2009', 'F'

SELECT * FROM @Occurrence

DECLARE @OccurrenceBucket TABLE(
        OccurrenceBucketID INT,
        FirstOccurrenceID INT,
        FirstOccurrenceTime DATETIME,
        FirstOccurrenceMessage VARCHAR(MAX)
)

INSERT INTO @OccurrenceBucket (OccurrenceBucketID) SELECT 1
INSERT INTO @OccurrenceBucket (OccurrenceBucketID) SELECT 2

SELECT * FROM @OccurrenceBucket


UPDATE  @OccurrenceBucket
SET     FirstOccurrenceID = OccurrenceID,
        FirstOccurrenceTime = OccurrenceTime,
        FirstOccurrenceMessage = OccurrenceMessage
FROM    @OccurrenceBucket oc INNER JOIN
        (
            SELECT  o.*
            FROM    @Occurrence o INNER JOIN
                    (
                        SELECT  OccurrenceBucketID,
                                MIN(OccurrenceID) FirstOccurrenceID
                        FROM    @Occurrence
                        GROUP BY OccurrenceBucketID
                    ) Mins ON o.OccurrenceID = mins.FirstOccurrenceID
        ) Vals ON oc.OccurrenceBucketID = Vals.OccurrenceBucketID

SELECT * FROM @OccurrenceBucket

编辑：

UPDATE  @OccurrenceBucket 
SET     FirstOccurrenceID = OccurrenceID, 
        FirstOccurrenceTime = OccurrenceTime, 
        FirstOccurrenceMessage = OccurrenceMessage 
FROM    @OccurrenceBucket oc INNER JOIN 
        ( 
                SELECT  o.* 
                FROM    @Occurrence o INNER JOIN 
                                ( 
                                        SELECT  OccurrenceBucketID, 
                                                        MIN(OccurrenceTime) FirstOccurrenceTime 
                                        FROM    @Occurrence 
                                        GROUP BY OccurrenceBucketID 
                                ) Mins ON o.OccurrenceTime = mins.FirstOccurrenceTime 
        ) Vals ON oc.OccurrenceBucketID = Vals.OccurrenceBucketID

【讨论】：

感谢您的意见。不幸的是，我们使用唯一标识符作为 ID，因此 MIN(OccurrenceID) 不起作用。你有其他方法来执行选择吗？
改变了解决方案，使用OccurenceTime

【解决方案2】：

那么，要找到存储桶中的第一个匹配项，不应该执行以下操作吗？

SELECT TOP 1
  OccurranceID, OccurranceTime, OccurranceMessage
FROM Occurance
WHERE
  OccurranceBucketID = @OccurranceBucketID
ORDER BY
  OccurranceTime ASC

您可以将返回的字段分配给变量，然后相应地更新您的 OccurranceBucket。

^{注意：“occurrence”中没有“a”。}

【讨论】：

【解决方案3】：

这个答案依赖于每个 Occurrence 的 OccurrenceTime：-

更新 OccBuck 集
OccBuck.FirstOccurrenceID = Occ.OccurrenceID,
OccBuck.FirstOccurrenceTime = Occ.OccurrenceTime,
OccBuck.FirstOccurrenceMessage = Occ.OccurrenceMessage
来自
dbo.OccurrenceBucket 作为 OccBuck
内部连接 dbo.Occurrence 作为 Occ 在 OccBuck.OccurrenceBucketID = Occ.OccurrenceBucketID
内连接（选择 OccurrenceBucketID，
MIN(OccurrenceTime) 作为 'MinOccurrenceTime'
来自 dbo.Occurrence
按 OccurrenceBucketID 分组）作为 Occ.OccurrenceBucketID= minOcc.OccurrenceBucketID 上的 minOcc 和
Occ.OccurrenceTime = minOcc.MinOccurrenceTime

【讨论】：