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How to check for overlapping dates in SQL?
You need to check start overlap and end overlap. In case, startdate is always less than endDate, following query can be used. The CTE is not required if you have some primary key: Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. Provide details and share your research!
How to determine if two date ranges overlap?
The short (ish) answer is: given two date intervals A and B with components .start and .end and the constraint .start <= .end, then two intervals overlap if: A.end >= B.start AND A.start <= B.end You can tune the use of >= vs > and <= vs < to meet your requirements for degree of overlap.
When do I need to compare two time spans in SQL?
When I needed to compare two time spans in SQL for overlap, here are the four scenarios I could think of: Here is the OR statement I created to capture these scenarios (in my case Oracle SQL): or something like that (assuming dates are not nullable and equal dates count as an overlap).
Is there a way to test for overlaps?
Comparing to test for overlaps is easy. You can compare an Interval against another Interval or Instant: All of these use the Half-Open approach to defining a span of time where the beginning is inclusive and the ending is exclusive. The mathematical solution given by @Bretana is good but neglects two specific details:
How to avoid overlapping ranges of data in a query?
For example if you are trying to write a trigger to prevent overlaps, the query can simply be put in an IF EXISTS (the query) THROW construct. If the query returns data, there is an issue. But if you want a list of all of the rows that have issues, the duplication of data can be confusing.
Is it possible for two events to overlap?
There are six different logical scenarios where two events could potentially be deemed to overlap, and many of the queries I see out in the wild treat all six of these scenarios separately. Only four of those scenarios might/can overlap.