MySQL Date and DATETIME Comparisons

Comparing date-like strings poses challenges when dealing with fields stored as DATETIME. Consider the database table calendar, where startTime is a DATETIME field. Selecting rows based on a date string, such as "2010-04-29," requires careful handling to match the DATETIME values accordingly.

SOLUTION:

To achieve the desired comparison, utilize the DATE() function:

SELECT * FROM `calendar` WHERE DATE(startTime) = '2010-04-29'

The DATE() function extracts the date component from a DATETIME value, effectively stripping away the time information. This ensures that the date string you defined ("2010-04-29") can be directly compared with the date extracted from the startTime DATETIME field.

PERFORMANCE OPTIMIZATION:

The DATE() function can be more efficient than alternative approaches for large tables. For instance, the SALIL solution using STRCMP took 4.48 seconds for a 2 million row table, while the DATE() approach completed in just 2.25 seconds. Consider the DATE() function for optimal performance in such scenarios.