How Can SQL Identify Consecutive Date Ranges Within a Dataset?

Detecting Consecutive Date Ranges with SQL

To determine consecutive date ranges within a column of dates, SQL techniques can be employed. Consider a scenario where a calendar object requires start and end date information, and a given column contains a series of dates, some of which are adjacent and others are not. To efficiently identify these consecutive ranges, a robust SQL solution is sought.

One approach involves exploiting the invariant property of consecutive sequences when grouping by the difference between date values and row numbers. The start and end dates within each group are then retrieved as the minimum and maximum values, respectively.

The following SQL query illustrates this approach:

WITH t AS (
  SELECT InfoDate d,ROW_NUMBER() OVER(ORDER BY InfoDate) i
  FROM @d
  GROUP BY InfoDate
)
SELECT MIN(d),MAX(d)
FROM t
GROUP BY DATEDIFF(day,i,d)

This query effectively groups the dates by their difference from their corresponding row numbers, resulting in distinct groups for each consecutive sequence. The minimum and maximum dates within each group are then selected to represent the start and end ranges.

By utilizing this method, the desired output can be obtained, providing a comprehensive list of consecutive date ranges sorted by the difference between their start and end dates.

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