How to Efficiently Retrieve MySQL Records for Specific Days, Ignoring Time?

Retrieving Records from Specific Days in MySQL Excluding Time

When working with temporal data stored as datetimes, it becomes necessary to retrieve records based on specific days without regard to time. This scenario arises frequently in applications that track daily metrics or analyze events within a given 24-hour period.

To achieve this, it is imperative to avoid using selectors such as DATE(datecolumns) = '2012-12-24', as they can significantly impact performance and prevent the utilization of indexes.

Instead, it is recommended to employ a range-based query using the BETWEEN operator. For example, the following query retrieves records from the specified table for December 25, 2012:

SELECT * FROM tablename 
WHERE columname BETWEEN '2012-12-25 00:00:00' AND '2012-12-25 23:59:59'

This approach allows for index utilization and ensures optimal query performance.

Recently, it has been discovered that using '23:59:59' as the end of a day may not be reliable in certain MySQL versions. To address this, it is advisable to update the query to the following:

SELECT * FROM tablename 
WHERE columname >= '2012-12-25 00:00:00' 
AND columname < '2012-12-26 00:00:00'

While the specific syntax may differ slightly depending on the MySQL version, the principle of excluding time-based comparisons and using range selectors remains crucial for efficient query performance.

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