mysqldatetime的简单介绍

MySQL Date and Time Functions

Introduction:

MySQL provides a wide range of built-in functions to manipulate date and time values. These functions are essential for various database operations that involve working with dates and times. In this article, we will explore the mysqldatetime, a useful date and time function in MySQL.

I. What is mysqldatetime?

The mysqldatetime function in MySQL is used to convert a given date and time into a MySQL compatible format. It takes a string or numeric value representing a date and time and converts it into the MySQL DATETIME format, which is 'YYYY-MM-DD HH:MM:SS' by default.

II. Syntax:

The syntax for using mysqldatetime function is as follows:

mysqldatetime(date_or_time_value)

III. Examples:

1. Convert a date string into MySQL DATETIME format:

Consider the following example:

SELECT mysqldatetime('2022-06-15');

Output: '2022-06-15 00:00:00'

The mysqldatetime function converts the given date string '2022-06-15' into the MySQL DATETIME format.

2. Convert a time value into MySQL DATETIME format:

Now, let's convert a time value into MySQL DATETIME format using the mysqldatetime function.

SELECT mysqldatetime('12:30:45');

Output: '0000-00-00 12:30:45'

The mysqldatetime function converts the given time value '12:30:45' into the MySQL DATETIME format. However, since the time value does not contain a date, the resulting MySQL DATETIME format has '0000-00-00' as the date part.

IV. Additional Information:

Some important points to remember while using the mysqldatetime function are as follows:

- The mysqldatetime function does not validate the input date or time value. It simply converts the given value into the MySQL DATETIME format.

- If the given date or time value is not in a valid format, the mysqldatetime function may produce unexpected results or return null.

- The mysqldatetime function can also be used along with other date and time functions in complex queries to perform various calculations or comparisons.

In conclusion, the mysqldatetime function in MySQL is a useful tool for converting date and time values into the MySQL DATETIME format. It provides a convenient way to manipulate and display date and time information in a standardized format.