从标识符中选择10 Before和10 After

时间：2016-06-15 19:23:42

标签： sql sql-server tsql sql-server-2008-r2

您认为SQL语句 BELOW 能否以比呈现方式更好的方式执行。

以下是要求：

  1. 查询需要TextIdentifier和用户名
  2. 识别之前创建的10个MP3文件，以及之后创建的10个MP3文件。
  3. 如果之前或之后存在少于10个MP3文件，则选择所有可用的文件。
  4. 由于DateCreated不相关
    5. ，因此无法使用表格中的自动编号ID
      

    代码位于图片

    下方

    以下是一些潜在的情况：

    enter image description here

    enter image description here

    enter image description here

    QUERY： 

     DECLARE @UserName NVARCHAR(255)
    DECLARE @TextIdentifier NVARCHAR(255)
    DECLARE @ProximityDate AS DATETIME
    SET @UserName = 'Pete'
    SET @TextIdentifier = '456'

    SELECT  @ProximityDate = [DateCreated]
    FROM    dbo.ProximitySelectTable
    WHERE   UserName = @UserName
            AND TextIdentifier = @TextIdentifier


    SELECT * FROM (

    SELECT TOP 10 *
    FROM    dbo.ProximitySelectTable
    WHERE   UserName = @UserName
            AND [DateCreated] < @ProximityDate
    UNION
    SELECT  *
    FROM    dbo.ProximitySelectTable
    WHERE   UserName = @UserName
            AND TextIdentifier = @TextIdentifier                      
    UNION
    SELECT TOP 10 *
    FROM    dbo.ProximitySelectTable
    WHERE   UserName = @UserName
            AND [DateCreated] > @ProximityDate        
    ) x
    ORDER BY x.DateCreated

    表格 

    CREATE TABLE [dbo].[ProximitySelectTable](
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [TextIdentifier] [nvarchar](255) NULL,
    [UserName] [nvarchar](255) NULL,
    [FileName] [nvarchar](255) NULL,
    [DateCreated] [datetime] NULL
) ON [PRIMARY]

    测试数据 

    /****** Object:  Table [dbo].[ProximitySelectTable]    Script Date: 06/15/2016 15:15:09 ******/
SET IDENTITY_INSERT [dbo].[ProximitySelectTable] ON
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (1, N'2has721', N'Pete', N'c:\123456.mp3', CAST(0x0000A13900000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (2, N'123', N'Pete', N'c:\223456.mp3', CAST(0x0000A58000000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (3, N'456', N'Pete', N'c:\323456.mp3', CAST(0x0000A5DB00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (4, N'789', N'Pete', N'c:\423456.mp3', CAST(0x0000A58000000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (5, N'1011', N'Pete', N'c:\523456.mp3', CAST(0x0000A5F900000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (6, N'1112', N'Jack', N'c:\623456.mp3', CAST(0x0000A5BC00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (7, N'1312', N'Jack', N'c:\723456.mp3', CAST(0x0000A56C00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (8, N'1412', N'Jack', N'c:\823456.mp3', CAST(0x0000A54300000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (9, N'1516', N'Jack', N'c:\923456.mp3', CAST(0x0000A58000000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (10, N'1817', N'Jack', N'c:\133456.mp3', CAST(0x0000A5F900000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (11, N'1819', N'Sherry', N'c:\143456.mp3', CAST(0x0000A52400000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (12, N'2021', N'Sherry', N'c:\153456.mp3', CAST(0x0000A5BC00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (13, N'2122', N'Sherry', N'c:\163456.mp3', CAST(0x0000A5DB00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (14, N'2123', N'Pete', N'c:\173456.mp3', CAST(0x0000A52400000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (15, N'2124', N'Pete', N'c:\183456.mp3', CAST(0x0000A13900000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (16, N'2125', N'Sherry', N'c:\193456.mp3', CAST(0x0000A50600000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (17, N'2126', N'Jack', N'c:\124456.mp3', CAST(0x0000A5BC00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (18, N'2127', N'Pete', N'c:\125456.mp3', CAST(0x0000A13900000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (19, N'2128', N'Sherry', N'c:\aaaa1.mp3', CAST(0x0000A4E700000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (20, N'2129', N'Jack', N'c:\aaaa2.mp3', CAST(0x0000A5F900000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (21, N'3121', N'Jack', N'c:\aaaa3.mp3', CAST(0x0000A13900000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (22, N'3122', N'Sherry', N'c:\aaaa4.mp3', CAST(0x0000A54300000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (23, N'3123', N'Jack', N'c:\aaaa5.mp3', CAST(0x0000A5BC00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (24, N'3124', N'Jack', N'c:\aaaa6.mp3', CAST(0x0000A13900000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (25, N'3125', N'Sherry', N'c:\aaaa7.mp3', CAST(0x0000A5DB00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (26, N'3126', N'Jack', N'c:\aaaa8.mp3', CAST(0x0000A56C00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (27, N'3127', N'Pete', N'c:\aaaa9.mp3', CAST(0x0000A5F900000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (28, N'3128', N'Pete', N'c:\bbbbb1.mp3', CAST(0x0000A54300000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (29, N'3129', N'Sherry', N'c:\bbbbb2.mp3', CAST(0x0000A5BC00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (30, N'4121', N'Jack', N'c:\bbbbb3.mp3', CAST(0x0000A52400000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (31, N'4122', N'Pete', N'c:\bbbbb4.mp3', CAST(0x0000A5F900000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (32, N'4123', N'Jack', N'c:\bbbbb5.mp3', CAST(0x0000A5DB00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (33, N'4124', N'Jack', N'c:\bbbbb6.mp3', CAST(0x0000A50600000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (34, N'4125', N'Sherry', N'c:\bbbbb7.mp3', CAST(0x0000A5BC00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (35, N'4126', N'Jack', N'c:\bbbbb8.mp3', CAST(0x0000A56C00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (36, N'4127', N'Jack', N'c:\bbbbb9.mp3', CAST(0x0000A4E700000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (37, N'4128', N'Jack', N'c:\cccccc1.mp3', CAST(0x0000A54300000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (38, N'4129', N'Pete', N'c:\cccccc2.mp3', CAST(0x0000A5DB00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (39, N'5121', N'Sherry', N'c:\cccccc3.mp3', CAST(0x0000A5BC00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (40, N'5122', N'Jack', N'c:\cccccc4.mp3', CAST(0x0000A56C00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (41, N'5123', N'Jack', N'c:\cccccc5.mp3', CAST(0x0000A54300000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (42, N'5124', N'Sherry', N'c:\cccccc6.mp3', CAST(0x0000A5DB00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (43, N'5125', N'Pete', N'c:\cccccc7.mp3', CAST(0x0000A5BC00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (44, N'5126', N'Jack', N'c:\cccccc8.mp3', CAST(0x0000A5DB00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (45, N'5127', N'Pete', N'c:\cccccc9.mp3', CAST(0x0000A4E700000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (46, N'5128', N'Pete', N'c:\ddddd1.mp3', CAST(0x0000A54300000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (47, N'5129', N'Pete', N'c:\ddddd2.mp3', CAST(0x0000A4E700000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (48, N'6121', N'Pete', N'c:\ddddd3.mp3', CAST(0x0000A5F900000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (49, N'6122', N'Pete', N'c:\ddddd4.mp3', CAST(0x0000A50600000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (50, N'6123', N'Pete', N'c:\ddddd5.mp3', CAST(0x0000A5BC00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (51, N'6124', N'Pete', N'c:\ddddd6.mp3', CAST(0x0000A52400000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (52, N'6125', N'Pete', N'c:\ddddd7.mp3', CAST(0x0000A5F900000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (53, N'6126', N'Pete', N'c:\ddddd8.mp3', CAST(0x0000A50600000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (54, N'6127', N'Pete', N'c:\ddddd9.mp3', CAST(0x0000A5DB00000000 AS DateTime))
INSERT [dbo].[ProximitySelectTable] ([ID], [TextIdentifier], [UserName], [FileName], [DateCreated]) VALUES (55, N'6128', N'Jack', N'c:\ddddd0.mp3', CAST(0x0000A5F900000000 AS DateTime))
SET IDENTITY_INSERT [dbo].[ProximitySelectTable] OFF

3 个答案:

答案 0 :(得分：2)

您当前的查询不正确（缺少ORDER BY且不需要UNION而不是UNION ALL），但使用正确的索引时，其固定版本可能效率最高。

我的row_number答案首先是

WITH CTE1
     AS (SELECT *,
                ROW_NUMBER() OVER (ORDER BY DateCreated) AS RN
         FROM   [ProximitySelectTable]
         WHERE  UserName = @UserName),
     CTE2
     AS (SELECT *,
                MAX(CASE
                      WHEN @TextIdentifier = TextIdentifier
                        THEN RN
                    END) OVER () AS FocusRN
         FROM   CTE1)
SELECT ID,
       TextIdentifier,
       UserName,
       FileName,
       DateCreated
FROM   CTE2
WHERE  RN BETWEEN FocusRN - 10 AND FocusRN + 10
ORDER  BY DateCreated

当前查询的固定版本

SELECT * FROM (
SELECT TOP 10 *
FROM    dbo.ProximitySelectTable
WHERE   UserName = @UserName
        AND [DateCreated] < @ProximityDate
ORDER BY [DateCreated] DESC 
UNION ALL
SELECT  *
FROM    dbo.ProximitySelectTable
WHERE   UserName = @UserName
        AND TextIdentifier = @TextIdentifier                      
UNION ALL
SELECT TOP 10 *
FROM    dbo.ProximitySelectTable
WHERE   UserName = @UserName
        AND [DateCreated] > @ProximityDate  
ORDER BY [DateCreated] ASC            
) x
ORDER BY x.DateCreated

这需要UserName, TextIdentifier的索引用于初始搜索，而UserName, DateCreated则需要TOP 10的搜索，而不是排序。

答案 1 :(得分：1)

没有一个运行SQL Server 2008的方便，但我检查了以下所有功能在2008年可用：

DECLARE @UserName       NVARCHAR(255) = 'Pete'
DECLARE @TextIdentifier NVARCHAR(255) = '456'

;WITH
    cte1 AS
    (
        SELECT      *,
                    ROW_NUMBER() OVER (ORDER BY DateCreated) AS RowNumber
        FROM        ProximitySelectTable
    ),
    cte2 AS
    (
        SELECT TOP 1
                    RowNumber
        FROM        cte1
        WHERE       UserName = @UserName AND TextIdentifier = @TextIdentifier
        ORDER BY    RowNumber
    )


SELECT      *
FROM        cte1, cte2
WHERE       cte1.RowNumber BETWEEN (cte2.RowNumber - 10) AND (cte2.RowNumber + 10)

cte1对从1到n的所有行进行编号。 cte2找到目标行的行号。最终SELECT只扫描过去10行和接下来的10行。

答案 2 :(得分：1)

以下是ROW_NUMBER解决方案的伪代码：

WITH cte1 AS (
SELECT desiredcolumns, ROW_NUMBER() OVER (ORDER BY DateCol) AS rn
FROM MyTable
),
cte2 AS (
SELECT ID, rn
FROM cte1
WHERE TextIdentifier = @TextIdentifier 
)
SELECT desiredcolumns
FROM cte1
CROSS JOIN cte2
WHERE cte1.rn > cte2.rn - 10
AND cte1.rn < cte2.rn + 9
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