Database Reference
In-Depth Information
NANVL returns a replacement value if the initial value is not
a number.
REMAINDER is a remainder or modulus function specifi-
cally for binary floating-point numbers.
Regular expression functions are REGEXP_INSTR,
REGEXPR_REPLACE, and REGEXPR_SUBSTR. These func-
tions essentially expand the search-and-replace capabilities of
INSTR, REPLACE, and SUBSTR to full pattern-matching reg-
ular expression capabilities. For more information, refer to the
section titled “Expressions” (on page 44) in this chapter and see
Chapter 14.
Note:
The essential difference between simple pattern matching and regular
expression matching is that simple pattern matching searches for patterns.
Regular expression matching searches for patterns allowing for replacement
and return of specific values found within a pattern.
New statistical aggregation functions are covered in detail in
Chapter 11. Statistical analysis can be extremely useful in data
warehouse and reporting environments. There is now extensive
capability in Oracle SQL for OLAP-type inter-row and cross-row
analysis, which was previously only available in expensive software
packages and add-ons such as Formula1.
CORR_{S | K} calculate Pearson's correlation coefficient,
measuring the strength of a linear relationship between two
variables. Plotting two variables on a graph results in a lot of
dots plotted from two axes. Pearson's correlation coefficient
can tell you how good the straight line is.
MEDIAN returns a median, middle, or interpolated value.
Quite literally, a median is the middle sequenced value in a
set of values. If a distribution is discontinuous and skewed or
just all over the place, the median will not be anywhere near a
mean or average of a set of values. A median is not always ter-
ribly useful.
Other statistical functions begin with “STATS.” The syntax
appears like this:
STATS_{BINOMIAL_TEST | CROSSTAB | F_TEST | KS_TEST |
MODE | MW_TEST | ONE_WAY_ANOVA | STATS_T_TEST_* |
STATS_WSR_TEST}
These functions provide various statistical goodies.
