如何在 MySQL 中比較 DATE 字串與 DATETIME 值？

Comparing DATE Strings with DATETIME Values in MySQL

This question delves into a common challenge: comparing a DATE string to a DATETIME value stored in a database. The user seeks to filter data using a date picker and retrieve the specific row with the DATETIME value corresponding to the selected DATE.

Solution:

To achieve this comparison, the query should use the DATE() function. This function extracts only the date component from a DATETIME value, allowing for a direct comparison with a DATE string.

Modified Query:

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

By using the DATE() function, the query effectively compares only the date portion of the DATETIME field, eliminating the time component. This ensures that the row with the DATETIME value of "2010-04-29 10:00" will be retrieved, regardless of the specific time.

Additional Considerations:

For large tables, performance optimization is crucial. In cases where the table contains millions of records, using the DATE() function is more efficient than directly comparing DATETIME values. Tests have shown that the DATE() function approach reduces query execution time significantly.

Therefore, when comparing DATE strings to DATETIME values in MySQL, the use of the DATE() function is highly recommended, especially for tables with a large number of records.

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