Database Reference
In-Depth Information
Figure 11.2
Using an Oracle
Built-in SQL
Aggregate
Function.
What are the available aggregate functions and how are they used? Let's go
through the definitions. Functions have been divided into different sections.
11.2.1.1
Simple Summary Functions
AVG(expression
). The average.
COUNT(*|expression)
. The number of rows in a query.
MIN(expression
). The minimum
.
MAX(expression
). The maximum.
SUM(expression)
. The sum.
can be anything: a column name, a single-row function
on a column name, or simple calculations such as two columns added
together. Anything you might place in the SELECT clause can be used as
an expression within a group function.
An
expression
11.2.1.2
Statistical Function Calculators
STDDEV(expression
). The standard deviation is the average differ-
ence from the mean. The mean is similar to the average.
VARIANCE(expression)
. The variance is the square of the standard
deviation and thus the average squared difference from the mean, or
the average deviation from the mean.
STDDEV_POP(expression)
. The population standard deviation.
