从一个表中获取所有日期并从另一个表中获取每个日期的总记录答案

【问题标题】：Get all dates from one table and get total records of each date from another table从一个表中获取所有日期并从另一个表中获取每个日期的总记录
【发布时间】：2015-02-24 05:52:41
【问题描述】：

我创建了一个存储过程，它将接受 startdate、enddate、timezone、user 和 host

并将显示给定日期范围内每一天的所有记录计数。

我使用LEFT OUTER JOIN为此创建了一个存储过程，下面是我的代码：

USE [database]
GO
/****** Object:  StoredProcedure [dbo].[sp_getPageViewCountDayWise]           Script Date: 24/02/2015 10:25:11 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[sp_getPageViewCountDayWise]

    -- Add the parameters for the stored procedure here
   --<@Param1, sysname, @p1> <Datatype_For_Param1, , int> = <Default_Value_For_Param1, , 0>,
    --<@Param2, sysname, @p2> <Datatype_For_Param2, , int> = <Default_Value_For_Param2, , 0>

    @startdate DATETIME,
    @enddate DATETIME,
    @timezone VARCHAR(6),
    @user varchar(500),
    @host VARCHAR(200)

AS
BEGIN

    SET NOCOUNT ON;

    IF NULLIF(@user, '') IS NULL
    begin 
        set @user = @host+'/%'
    end 
    else
    begin
        set @user = @host+'/'+@user+'/%'
    end

   select * from [dbo].[ExplodeDates](@startdate,@enddate)

    select CAST(a.DateTime AS DATE) AS Date, count(*) as count
    from [dbo].[DateRange](@startdate,@enddate) AS b 
    LEFT OUTER JOIN UserLog AS a
    ON CAST(b.thedate AS DATE) = CAST(dbo.[ConvertDateToFromTimeZone]   (a.DateTime, @timezone) AS DATE) 
   and a.Url like @user
    group by CAST(a.DateTime AS date)

   END

[dbo].[DateRange] 是一个用户定义的函数，它将返回一个包含特定日期范围内所有日期的表格，如下所示：

GO
/****** Object:  UserDefinedFunction [dbo].[ExplodeDates]    Script Date:       24/02/2015 11:12:38 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER FUNCTION [dbo].[ExplodeDates](@startdate datetime, @enddate   datetime)
returns table as
return (
with 
 N0 as (SELECT 1 as n UNION ALL SELECT 1)
,N1 as (SELECT 1 as n FROM N0 t1, N0 t2)
,N2 as (SELECT 1 as n FROM N1 t1, N1 t2)
,N3 as (SELECT 1 as n FROM N2 t1, N2 t2)
,N4 as (SELECT 1 as n FROM N3 t1, N3 t2)
,N5 as (SELECT 1 as n FROM N4 t1, N4 t2)
,N6 as (SELECT 1 as n FROM N5 t1, N5 t2)
,nums as (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 1)) as num FROM N6)
SELECT DATEADD(day,num-1,@startdate) as thedate
FROM nums
WHERE num <= DATEDIFF(day,@startdate,@enddate) + 1
);

和

dbo.[ConvertDateToFromTimeZone] 是将每个日期转换为给定时区的函数

GO
/****** Object:  UserDefinedFunction [dbo].[ConvertDateToFromTimeZone]       Script Date: 24/02/2015 11:14:03 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER FUNCTION [dbo].[ConvertDateToFromTimeZone]
(
   -- Add the parameters for the function here
    @date DATETIMEOFFSET,
    @offset VARCHAR(6)
)
RETURNS DATETIME
AS
BEGIN
   -- Declare the return variable here
   DECLARE @Result DATETIME

   -- Add the T-SQL statements to compute the return value here
    SELECT @Result= SWITCHOFFSET (@date , @offset)
    -- Return the result of the function
    RETURN @Result

END

假设我想查看每天 2015 年 2 月 2 日到 2015 年 2 月 5 日之间的记录数，结果应该是

Date        Count
02/02/2015    10
03/02/2015     2
04/02/2015     0
05/02/2015     3

但我的程序正在返回类似这样的内容

Date          Count
NULL           2
02/02/2015     10
03/02/2015     2
05/02/2015     3

我做错了什么？

【问题讨论】：

标签： sql sql-server datetime stored-procedures

【解决方案1】：

a.DateTime 是左连接的右侧，因此可以返回空值。看来您想要连接的左侧，即b.thedate。因此，您应该在查询中选择 b.thedate 而不是 a.DateTime（并且很可能也按此分组）。

【讨论】：