How to Efficiently Count Records by Date Within a Specified Range?

Calculating Record Counts for Each Date within a Specified Range

In the realm of data analysis, it's often necessary to determine the number of records created over a time period. The task at hand involves querying a dataset to count unique Ids within a date range. However, executing this query using the provided code snippet encounters an "Operand type clash" error.

Delving into the Original Attempt

The initial approach utilizes a recursive CTE (Common Table Expression) to generate a sequence of dates within the specified range. However, the crucial error arises when attempting to subtract integers from datetime2 values, leading to incompatibility issues.

Leveraging a Tally Table

To overcome this obstacle and achieve optimum performance, consider employing a tally table or function. Itzik Ben-Gan's highly regarded tally table implementation is exemplified below:

WITH
    L0 AS ( ... ),
    L1 AS ( ... ),
    L2 AS ( ... ),
    Nums AS ( ... ),
    Date_Range_T (d_range) AS (
      SELECT ...
    )

This approach enables the generation of a sequence of dates within the specified range, providing the foundation for calculating record counts.

Joining with the Target Table and Grouping

Subsequently, the Date_Range_T table is left joined with the tbl_Support_Requests table using appropriate date filters to retrieve Ids created within each date range. The results are then grouped by d_range to obtain the total count of Ids.

By applying this method, you can effectively calculate the number of records for each date within the specified range, providing valuable insights for data analysis and visualization.

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