June 2015
Beginner
140 pages
3h
English
Content preview from Getting Started with MariaDBBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Summarizing data
Sometimes, we are just looking for information about our data. For this, MariaDB has several built-in functions: AVG, COUNT, MIN, MAX, and SUM.
The AVG function
The AVG function is used for obtaining the average of the data in a column. For example, combined with the TIMESTAMPDIFF and CURDATE functions, we can use the AVG function to calculate the average age of all of the people in the employees table.
The CURDATE function doesn't take any arguments and when called, it simply returns the current date.
The TIMESTAMPDIFF function takes three arguments—the unit to count by and two dates, and then outputs the difference between the two. The unit is one of several time units, including MINUTE, HOUR, DAY, WEEK, MONTH, QUARTER, and YEAR ...
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