Date Arithmetic With MySQL
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If you're familiar with MySQL, one of the planet's most popular open-source RDBMS, you already know that it supports a wide variety of data types for numbers, strings and dates. These data types perform two very important
functions: they enforce consistency on the data in a MySQL table (ensuring, for example, that numeric columns do not contain character data) and they optimize the space (bytes) required to store each type of data.
Now, MySQL comes with almost different data types, including types for integers, floating-point numbers, strings, date and time values, and data collections. One of the larger categories among these is the one containing date and time types, primarily because MySQL includes date and time types to meet almost every need you could think of. For example, there's the TIMESTAMP type to store timestamps, the DATE and TIME types to store just dates or times, the hybrid DATETIME type to store both, and the YEAR type to store the year component of a date.
Of course, data types, by themselves are only one piece of the puzzle; in order to do something with them, you need functions. And MySQL scores high points there as well, providing over 40 built-in functions to process and manipulate date and time values. The MySQL date and time API includes functions to extract different components of a timestamp, to format a timestamp in a variety of different ways, to obtain the current date and time, to convert between different date and time formats, and much, much more.
Sadly, this article isn't going to examine the complete date and time API in MySQL; instead, it's going to focus on a very small subset of this API, the functions related to performing date and time arithmetic. Flip the page, and let's get started.
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