Can NULL Values Be Stored in MySQL Datetime Fields?

Storing NULL Values in MySQL Datetime Fields

NULL values are commonly used in database systems to represent missing or unknown data. However, managing NULL values in datetime fields in MySQL can be tricky.

MySQL Supports NULL Datetime Values

Contrary to the concern raised in the original question, MySQL does allow NULL values in datetime fields. As demonstrated in the test provided in the answer, inserting a NULL value into a datetime field using the INSERT INTO statement works as expected.

PHP Handling of NULL Datetime Values

The problem encountered when updating records using PHP is likely due to the assumption that an empty variable ($bill_date) translates to a NULL value in MySQL. However, this is not the case. To explicitly set a datetime field to NULL, you must explicitly send the word "NULL" or leave it out of the update query altogether.

Prepared Statements Recommended

For best practices, it is highly recommended to use prepared statements when interacting with databases from PHP. This ensures that variables are correctly bound and handled, avoiding potential errors like the one encountered in the provided example.

By following these guidelines, you can effectively store and manage NULL values in datetime fields in MySQL, both when using SQL commands and when programming with PHP.

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