MySQL: Defining Dates and Their Formats（mysql定义日期）
MySQL is one of the most popular databases used by developers. It allows users to create, update and delete information from their databases quickly and easily. However, one of the most challenging aspects of programming with MySQL is defining dates and their formats. This can be a difficult task due to the wide range of available date formats, as well as the various ways in which MySQL can interpret dates.
When defining dates, there are several different formats that can be used. The most common format is the traditional “YYYY-MM-DD” format. This is the American format and is the easiest to work with. Examples of this type of format include “2020-10-08” or “1994-05-11”. This format can be used in all versions of MySQL, regardless of the database type.
Another popular date format is the ISO 8601 format. This format is used primarily in Europe and is designated with the letter ‘T’. The format is “YYYY-MM-DDT HH:MM:SS”. Examples of this type of date include “2020-10-08T 11:30:00” or “1994-05-11T 17:00:00”. The ISO 8601 format is primarily used for date calculations, rather than for storage of the date in the database itself.
The other frequently used formats are the Julian day and internal format. The Julian day is represented as a decimal value, where day one starts at the beginning of 1947. When converting dates to the Julian day format, the output is the number of days since day one. The internal format is a numerical representation of the date as stored in the database, and is often used in databases that are connected to computers.
When it comes to storage of dates in the database, MySQL supports two commonly used date formats. These are the ISO 8601 and the Julian day formats. However, MySQL does not support the traditional “YYYY-MM-DD” format. To use this format, one must use the DATE_FORMAT() function and convert the date to the desired format.
In conclusion, when it comes to dates and their formats in MySQL, there are several different options. It is important to be aware of the various formats and their uses to ensure that the data is formatted correctly and stored in the database efficiently. Whether working with the traditional “YYYY-MM-DD” format or with more specialized formats such as the Julian day and internal format, having a good understanding of dates and their formats in MySQL is essential.
