How to Show All Dates Between Two Dates, Including Zero Values for Missing Dates?

Showing All Date Data Between Two Dates, Including Zero Values

When working with date data, it's common to encounter scenarios where not all dates are represented in your dataset. This can lead to gaps in your analysis. To address this issue and display all dates within a specified range, we can utilize a combination of techniques.

Let's consider the following problem:

We have a table named @temp with the following structure:

DECLARE @temp TABLE (
    ID INT IDENTITY(1,1) NOT NULL,
    CDate SMALLDATETIME,
    Val INT
)

The table содержит data from October 2, 2012 to October 15, 2012. However, we want to retrieve all dates between October 1, 2012 and October 15, 2012, and display zero values for any missing dates.

One approach to handle this is using a recursive common table expression (CTE) with a calendar table to generate all dates within the specified range. The CTE is defined as follows:

;WITH d(date) AS (
    SELECT CAST('10/01/2012' AS DATETIME),
    UNION ALL
    SELECT date + 1
    FROM d
    WHERE date < '10/15/2012'
)

This CTE generates all dates from October 1, 2012 to October 15, 2012.

Next, we join the CTE with the @temp table to retrieve the corresponding values for each date, handling missing dates by using the ISNULL NULL handling function, as shown in the following query:

SELECT t.ID, d.date AS CDate, ISNULL(t.val, 0) AS val
FROM d
LEFT JOIN temp t ON t.CDate = d.date
ORDER BY d.date
OPTION (MAXRECURSION 0)

The OPTION (MAXRECURSION 0) is used to limit the number of recursions in the CTE, ensuring the query does not run indefinitely. By setting this to 0, it allows unlimited recursion.

This query will produce the desired result, displaying all dates between October 1, 2012 and October 15, 2012, with zero values for any missing dates.

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