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Learning MySQL and MariaDB by Russell J.T. Dyer

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Chapter 12. Aggregate and Numeric Functions

Databases will always include numbers: there’s always something to value, count, or calculate. And you may want to round the results from those numbers to conform to personal preferences. There are numeric and arithmetic functions to do these things in MySQL and MariaDB. Some are known as aggregate functions. We will cover almost all of the aggregate and many numeric functions in this chapter. We won’t cover the more advanced functions related to statistics, or the mathematical functions related to calculus and geometry. Instead, we will cover the most useful and most used functions and leave the others for you to learn later on your own as you need them.

Aggregate Functions

Statistics can provide us with useful information about a database. If a database includes information about the activities of an organization, we can determine some statistical information about those activities. If a database includes numeric values associated with items an organization sells or tracks, statistics can provide us with information for making decisions about those items.

In our birdwatchers database, we can use aggregate functions to understand the behavior of our members in relation to our bird-watchers website, the events they attend, and other activities. For our rookery database, we can ascertain some information about birds using aggregate functions. That can be useful to our members related to searching for birds in the wild, as well as their concerns ...

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