Chapter 10. Aggregate Clauses, Aggregate Functions, and Subqueries
MySQL has many built-in functions that you can use in SQL statements
for performing calculations on combinations of values in databases; these
are called aggregate functions. They include such
types of basic statistical analysis as counting rows, determining the
average of a given column’s value, finding the standard deviation, and so
forth. The first section of this chapter describes MySQL aggregate functions
and includes examples of most of them. The second section provides a
tutorial about subqueries. It includes several examples of subqueries in
addition to the ones shown in the first section and in various examples
throughout this book. Subqueries are included in this chapter because they
are often used with GROUP BY
and aggregate functions and
because they’re another method for grouping selected data.
The following functions are covered in this chapter:
AVG(), BIT_AND(), BIT_OR(), COUNT(), GROUP_CONCAT(), MAX(), MIN(), STD(), STDDEV(), STDDEV_POP(), STDDEV_SAMP(), SUM(), VAR_POP(), VAR_SAMP(), VARIANCE().
Get MySQL in a Nutshell, 2nd Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.