按日期sql查询不会返回与日期范围相同范围内的日期sql查询相同的结果

Question

I am writing some sql to create reports. For the purpose of the reports, I need to get results by day, vs results over the entire date range. However, for many data samples, I am actually getting slightly different results (with the by day results always being the larger value). Perhaps someone can elucidate an edge case I am missing or some such. From what I can tell both queries cover the exact same time period.

By Day:

DECLARE @VarDate Datetime;
   SET @VarDate = '2018-07-01';
   WHILE @VarDate <= '2018-07-05'
   BEGIN
      IF EXISTS(SELECT CName, OrderNum, ODescription,
    PDescription, SUM(Qty) as TotalQty, Count(Qty) as Loads
    FROM TICKET
    WHERE TicketDate BETWEEN @VarDate + '00:00:00.00'
    AND @VarDate + '23:59:59.999' GROUP BY CName, OrderNum, ODescription, PDescription)
        SELECT CName, OrderNum, ODescription,
    PDescription, SUM(Qty) as TotalQty, Count(Qty) as Loads
    FROM TICKET
    WHERE TicketDate BETWEEN @VarDate + '00:00:00.00'
    AND @VarDate + '23:59:59.999' GROUP BY CName, OrderNum, ODescription, PDescription
   ELSE
      SELECT @VarDate as Date;
      SET @VarDate = DATEADD(DAY, 1, @VarDate);
   END

Regular Date Range:

SELECT CName, OrderNum, ODescription, PDescription,
       SUM(Qty) as TotalQty, Count(Qty) as Loads
    from TICKET WHERE TicketDate BETWEEN '2018-07-01 00:00:00.00'
     AND '2018-07-05 23:59:59.999' GROUP BY CName, OrderNum, ODescription, PDescription

EDIT: I actually need to use both of these methods for different options in the report. To clarify, the crux of my question is if anyone can tell me why these two queries would return different "Loads" totals for a different count of rows returned in total aggregate?

Answer 1

The actual issue was SQL Server was rounding '23:59:59.999' up, and thus counting '00:00:00.000' twice, which is what was counting these values twice, hence the larger values. Not sure why the SQL is rounding the number up, but I hope this helps someone.

Answer 2

If you need daily result between date range, you don't need to do WHILE. Also, how you will present this report?

As much as I understand I have created a sample :

DECLARE @DateFrom   DATETIME='2018-07-01';
DECLARE @DateTo     DATETIME='2018-07-05';

SELECT    CName
        , OrderNum
        , ODescription
        , PDescription
        , CAST(TicketDate AS DATE)
        , SUM(Qty) as TotalQty
        , Count(Qty) as Loads
FROM TICKET
WHERE CAST(TicketDate AS DATE) BETWEEN @DateFrom and @DateTo
GROUP BY  CName
        , OrderNum
        , ODescription
        , PDescription
        , CAST(TicketDate AS DATE);

Answer 3

I can't replicate the issue, however, if your goal is to have a row for every date, then the likely answer is the final example here. All 3 of these methods give different results. The first (a WHILE ) gives a dataset for each day; likely far from ideal. The WHILE is also (in many people's opinion) the worst solution here as it is an iterative task on a product designed specifically for dataset based tasks (which an iterative task is not). The second, using BETWEEN gives a single dataset, but only for days that appear in the table. The last gives a row for every date in the date range, even if they are not in the table.

CREATE TABLE dbo.SomeTable (ID int IDENTITY(1,1),
                            SomeDate date,
                            SomeNumber int);
INSERT INTO dbo.SomeTable (SomeDate,SomeNumber)
VALUES ('20181201',12),
       ('20181201',10),
       ('20181203',9),
       ('20181204',8),
       ('20181205',1),
       ('20181205',19);

GO

--Cursor
DECLARE @StartDate date, @EndDate date, @CurrDate date;
SET @StartDate = '20181201';
SET @EndDate = '20181205';
SET @CurrDate = @StartDate;

WHILE @CurrDate <= @EndDate BEGIN
    SELECT SomeDate,
           SUM(SomeNumber) AS TotalSomeNumber
    FROM dbo.SomeTable
    WHERE SomeDate = @CurrDate
    GROUP BY SomeDate;

    SET @CurrDate = DATEADD(DAY, 1, @CurrDate);
END

GO

--BETWEEN

DECLARE @StartDate date, @EndDate date;
SET @StartDate = '20181201';
SET @EndDate = '20181205';

SELECT SomeDate,
        SUM(SomeNumber) AS TotalSomeNumber
FROM dbo.SomeTable
WHERE SomeDate BETWEEN @StartDate AND @EndDate
GROUP BY SomeDate;

GO
--Calendar Table
DECLARE @StartDate date, @EndDate date;
SET @StartDate = '20181201';
SET @EndDate = '20181205';

WITH N AS(
    SELECT N
    FROM (VALUES(NULL),(NULL),(NULL),(NULL),(NULL)) N(N)),
Tally AS(
    SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL))-1 AS I
    FROM N),
Dates AS(
    SELECT DATEADD(DAY, I, @StartDate) AS [Date]
    FROM Tally
    WHERE DATEADD(DAY, I, @StartDate) <= @EndDate)
SELECT D.[Date] AS SomeDate,
       ISNULL(SUM(SomeNumber),0) AS TotalSomeNumber
FROM Dates D
     LEFT JOIN dbo.SomeTable ST ON D.[Date] = ST.SomeDate
GROUP BY D.[Date];


GO
DROP TABLE dbo.SomeTable;

It is worth noting that I created the Calendar "table" on the fly in this example. You would likely want to create a table with dates on your SQL Server. There are 100's of examples on out there on how to create one. They are a staple for a DBMS, and I suggest implementing one if you don't already have one.