How to Group Records by Date in MySQL When Only DATETIME Values Exist?

Converting DATETIME to DATE in MySQL

When working with databases, it's often necessary to group records by date. However, if the database only stores DATETIME values instead of DATE values, you may face challenges when performing these operations.

To resolve this, MySQL provides several functions that allow you to modify DATETIME values. One such function is DATE(), which takes a DATETIME argument and returns only the date portion, excluding the time. This can be extremely useful for grouping records based on date.

For example, consider the following query:

select * from follow_queue group by follow_date cast follow_date as date

This query groups records by the follow_date column. However, since follow_date contains DATETIME values, casting it to DATE is necessary to extract only the date portion. This is done using the CAST() function, as seen in the query.

However, it's important to note that the query provided in the problem statement is not valid. To achieve the desired result, the syntax should be corrected to:

select * from follow_queue group by DATE(follow_date)

This query uses the DATE() function directly to extract the date portion from the follow_date column. The DATE() function returns a DATE value, which can be used for grouping operations. By using this function, you can obtain the desired result of grouping records by date, even if the database only stores DATETIME values.

The above is the detailed content of How to Group Records by Date in MySQL When Only DATETIME Values Exist?. For more information, please follow other related articles on the PHP Chinese website!