| Current File : //usr/share/doc/postgresql-9.2.24/html/functions-aggregate.html |
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>Aggregate Functions</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REV="MADE"
HREF="mailto:pgsql-docs@postgresql.org"><LINK
REL="HOME"
TITLE="PostgreSQL 9.2.24 Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="Functions and Operators"
HREF="functions.html"><LINK
REL="PREVIOUS"
TITLE="Range Functions and Operators"
HREF="functions-range.html"><LINK
REL="NEXT"
TITLE="Window Functions"
HREF="functions-window.html"><LINK
REL="STYLESHEET"
TYPE="text/css"
HREF="stylesheet.css"><META
HTTP-EQUIV="Content-Type"
CONTENT="text/html; charset=ISO-8859-1"><META
NAME="creation"
CONTENT="2017-11-06T22:43:11"></HEAD
><BODY
CLASS="SECT1"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="5"
ALIGN="center"
VALIGN="bottom"
><A
HREF="index.html"
>PostgreSQL 9.2.24 Documentation</A
></TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
TITLE="Range Functions and Operators"
HREF="functions-range.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="functions.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="60%"
ALIGN="center"
VALIGN="bottom"
>Chapter 9. Functions and Operators</TD
><TD
WIDTH="20%"
ALIGN="right"
VALIGN="top"
><A
TITLE="Window Functions"
HREF="functions-window.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="FUNCTIONS-AGGREGATE"
>9.20. Aggregate Functions</A
></H1
><P
> <I
CLASS="FIRSTTERM"
>Aggregate functions</I
> compute a single result
from a set of input values. The built-in aggregate functions
are listed in
<A
HREF="functions-aggregate.html#FUNCTIONS-AGGREGATE-TABLE"
>Table 9-46</A
> and
<A
HREF="functions-aggregate.html#FUNCTIONS-AGGREGATE-STATISTICS-TABLE"
>Table 9-47</A
>.
The special syntax considerations for aggregate
functions are explained in <A
HREF="sql-expressions.html#SYNTAX-AGGREGATES"
>Section 4.2.7</A
>.
Consult <A
HREF="tutorial-agg.html"
>Section 2.7</A
> for additional introductory
information.
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-AGGREGATE-TABLE"
></A
><P
><B
>Table 9-46. General-Purpose Aggregate Functions</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><COL><THEAD
><TR
><TH
>Function</TH
><TH
>Argument Type(s)</TH
><TH
>Return Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>array_agg(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
> any
</TD
><TD
> array of the argument type
</TD
><TD
>input values, including nulls, concatenated into an array</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>avg(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>smallint</TT
>, <TT
CLASS="TYPE"
>int</TT
>,
<TT
CLASS="TYPE"
>bigint</TT
>, <TT
CLASS="TYPE"
>real</TT
>, <TT
CLASS="TYPE"
>double
precision</TT
>, <TT
CLASS="TYPE"
>numeric</TT
>, or <TT
CLASS="TYPE"
>interval</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>numeric</TT
> for any integer-type argument,
<TT
CLASS="TYPE"
>double precision</TT
> for a floating-point argument,
otherwise the same as the argument data type
</TD
><TD
>the average (arithmetic mean) of all input values</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>bit_and(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>smallint</TT
>, <TT
CLASS="TYPE"
>int</TT
>, <TT
CLASS="TYPE"
>bigint</TT
>, or
<TT
CLASS="TYPE"
>bit</TT
>
</TD
><TD
> same as argument data type
</TD
><TD
>the bitwise AND of all non-null input values, or null if none</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>bit_or(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>smallint</TT
>, <TT
CLASS="TYPE"
>int</TT
>, <TT
CLASS="TYPE"
>bigint</TT
>, or
<TT
CLASS="TYPE"
>bit</TT
>
</TD
><TD
> same as argument data type
</TD
><TD
>the bitwise OR of all non-null input values, or null if none</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>bool_and(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>bool</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>bool</TT
>
</TD
><TD
>true if all input values are true, otherwise false</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>bool_or(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>bool</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>bool</TT
>
</TD
><TD
>true if at least one input value is true, otherwise false</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>count(*)</CODE
>
</TD
><TD
> </TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>number of input rows</TD
></TR
><TR
><TD
><CODE
CLASS="FUNCTION"
>count(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
></TD
><TD
>any</TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
> number of input rows for which the value of <TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
> is not null
</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>every(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>bool</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>bool</TT
>
</TD
><TD
>equivalent to <CODE
CLASS="FUNCTION"
>bool_and</CODE
></TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>max(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
>any array, numeric, string, or date/time type</TD
><TD
>same as argument type</TD
><TD
> maximum value of <TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
> across all input
values
</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>min(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
>any array, numeric, string, or date/time type</TD
><TD
>same as argument type</TD
><TD
> minimum value of <TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
> across all input
values
</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
> string_agg(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>,
<TT
CLASS="REPLACEABLE"
><I
>delimiter</I
></TT
>)
</CODE
>
</TD
><TD
> (<TT
CLASS="TYPE"
>text</TT
>, <TT
CLASS="TYPE"
>text</TT
>) or (<TT
CLASS="TYPE"
>bytea</TT
>, <TT
CLASS="TYPE"
>bytea</TT
>)
</TD
><TD
> same as argument types
</TD
><TD
>input values concatenated into a string, separated by delimiter</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>sum(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>smallint</TT
>, <TT
CLASS="TYPE"
>int</TT
>,
<TT
CLASS="TYPE"
>bigint</TT
>, <TT
CLASS="TYPE"
>real</TT
>, <TT
CLASS="TYPE"
>double
precision</TT
>, <TT
CLASS="TYPE"
>numeric</TT
>,
<TT
CLASS="TYPE"
>interval</TT
>, or <TT
CLASS="TYPE"
>money</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>bigint</TT
> for <TT
CLASS="TYPE"
>smallint</TT
> or
<TT
CLASS="TYPE"
>int</TT
> arguments, <TT
CLASS="TYPE"
>numeric</TT
> for
<TT
CLASS="TYPE"
>bigint</TT
> arguments, otherwise the same as the
argument data type
</TD
><TD
>sum of <TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
> across all input values</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>xmlagg(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>xml</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>xml</TT
>
</TD
><TD
>concatenation of XML values (see also <A
HREF="functions-xml.html#FUNCTIONS-XML-XMLAGG"
>Section 9.14.1.7</A
>)</TD
></TR
></TBODY
></TABLE
></DIV
><P
> It should be noted that except for <CODE
CLASS="FUNCTION"
>count</CODE
>,
these functions return a null value when no rows are selected. In
particular, <CODE
CLASS="FUNCTION"
>sum</CODE
> of no rows returns null, not
zero as one might expect, and <CODE
CLASS="FUNCTION"
>array_agg</CODE
>
returns null rather than an empty array when there are no input
rows. The <CODE
CLASS="FUNCTION"
>coalesce</CODE
> function can be used to
substitute zero or an empty array for null when necessary.
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> Boolean aggregates <CODE
CLASS="FUNCTION"
>bool_and</CODE
> and
<CODE
CLASS="FUNCTION"
>bool_or</CODE
> correspond to standard SQL aggregates
<CODE
CLASS="FUNCTION"
>every</CODE
> and <CODE
CLASS="FUNCTION"
>any</CODE
> or
<CODE
CLASS="FUNCTION"
>some</CODE
>.
As for <CODE
CLASS="FUNCTION"
>any</CODE
> and <CODE
CLASS="FUNCTION"
>some</CODE
>,
it seems that there is an ambiguity built into the standard syntax:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT b1 = ANY((SELECT b2 FROM t2 ...)) FROM t1 ...;</PRE
><P>
Here <CODE
CLASS="FUNCTION"
>ANY</CODE
> can be considered either as introducing
a subquery, or as being an aggregate function, if the subquery
returns one row with a Boolean value.
Thus the standard name cannot be given to these aggregates.
</P
></BLOCKQUOTE
></DIV
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> Users accustomed to working with other SQL database management
systems might be disappointed by the performance of the
<CODE
CLASS="FUNCTION"
>count</CODE
> aggregate when it is applied to the
entire table. A query like:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT count(*) FROM sometable;</PRE
><P>
will require effort proportional to the size of the table:
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> will need to scan either the
entire table or the entirety of an index which includes all rows in
the table.
</P
></BLOCKQUOTE
></DIV
><P
> The aggregate functions <CODE
CLASS="FUNCTION"
>array_agg</CODE
>,
<CODE
CLASS="FUNCTION"
>string_agg</CODE
>,
and <CODE
CLASS="FUNCTION"
>xmlagg</CODE
>, as well as similar user-defined
aggregate functions, produce meaningfully different result values
depending on the order of the input values. This ordering is
unspecified by default, but can be controlled by writing an
<TT
CLASS="LITERAL"
>ORDER BY</TT
> clause within the aggregate call, as shown in
<A
HREF="sql-expressions.html#SYNTAX-AGGREGATES"
>Section 4.2.7</A
>.
Alternatively, supplying the input values from a sorted subquery
will usually work. For example:
</P><PRE
CLASS="SCREEN"
>SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;</PRE
><P>
But this syntax is not allowed in the SQL standard, and is
not portable to other database systems.
</P
><P
> <A
HREF="functions-aggregate.html#FUNCTIONS-AGGREGATE-STATISTICS-TABLE"
>Table 9-47</A
> shows
aggregate functions typically used in statistical analysis.
(These are separated out merely to avoid cluttering the listing
of more-commonly-used aggregates.) Where the description mentions
<TT
CLASS="REPLACEABLE"
><I
>N</I
></TT
>, it means the
number of input rows for which all the input expressions are non-null.
In all cases, null is returned if the computation is meaningless,
for example when <TT
CLASS="REPLACEABLE"
><I
>N</I
></TT
> is zero.
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-AGGREGATE-STATISTICS-TABLE"
></A
><P
><B
>Table 9-47. Aggregate Functions for Statistics</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><COL><THEAD
><TR
><TH
>Function</TH
><TH
>Argument Type</TH
><TH
>Return Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>corr(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
>correlation coefficient</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>covar_pop(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
>population covariance</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>covar_samp(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
>sample covariance</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>regr_avgx(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
>average of the independent variable
(<TT
CLASS="LITERAL"
>sum(<TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)/<TT
CLASS="REPLACEABLE"
><I
>N</I
></TT
></TT
>)</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>regr_avgy(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
>average of the dependent variable
(<TT
CLASS="LITERAL"
>sum(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>)/<TT
CLASS="REPLACEABLE"
><I
>N</I
></TT
></TT
>)</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>regr_count(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>bigint</TT
>
</TD
><TD
>number of input rows in which both expressions are nonnull</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>regr_intercept(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
>y-intercept of the least-squares-fit linear equation
determined by the (<TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>) pairs</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>regr_r2(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
>square of the correlation coefficient</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>regr_slope(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
>slope of the least-squares-fit linear equation determined
by the (<TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>,
<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>) pairs</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>regr_sxx(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
><TT
CLASS="LITERAL"
>sum(<TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>^2) - sum(<TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)^2/<TT
CLASS="REPLACEABLE"
><I
>N</I
></TT
></TT
> (<SPAN
CLASS="QUOTE"
>"sum of
squares"</SPAN
> of the independent variable)</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>regr_sxy(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
><TT
CLASS="LITERAL"
>sum(<TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>*<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>) - sum(<TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>) * sum(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>)/<TT
CLASS="REPLACEABLE"
><I
>N</I
></TT
></TT
> (<SPAN
CLASS="QUOTE"
>"sum of
products"</SPAN
> of independent times dependent
variable)</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>regr_syy(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
>
</TD
><TD
><TT
CLASS="LITERAL"
>sum(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>^2) - sum(<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>)^2/<TT
CLASS="REPLACEABLE"
><I
>N</I
></TT
></TT
> (<SPAN
CLASS="QUOTE"
>"sum of
squares"</SPAN
> of the dependent variable)</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>stddev(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>smallint</TT
>, <TT
CLASS="TYPE"
>int</TT
>,
<TT
CLASS="TYPE"
>bigint</TT
>, <TT
CLASS="TYPE"
>real</TT
>, <TT
CLASS="TYPE"
>double
precision</TT
>, or <TT
CLASS="TYPE"
>numeric</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
> for floating-point arguments,
otherwise <TT
CLASS="TYPE"
>numeric</TT
>
</TD
><TD
>historical alias for <CODE
CLASS="FUNCTION"
>stddev_samp</CODE
></TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>stddev_pop(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>smallint</TT
>, <TT
CLASS="TYPE"
>int</TT
>,
<TT
CLASS="TYPE"
>bigint</TT
>, <TT
CLASS="TYPE"
>real</TT
>, <TT
CLASS="TYPE"
>double
precision</TT
>, or <TT
CLASS="TYPE"
>numeric</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
> for floating-point arguments,
otherwise <TT
CLASS="TYPE"
>numeric</TT
>
</TD
><TD
>population standard deviation of the input values</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>stddev_samp(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)</CODE
>
</TD
><TD
> <TT
CLASS="TYPE"
>smallint</TT
>, <TT
CLASS="TYPE"
>int</TT
>,
<TT
CLASS="TYPE"
>bigint</TT
>, <TT
CLASS="TYPE"
>real</TT
>, <TT
CLASS="TYPE"
>double
precision</TT
>, or <TT
CLASS="TYPE"
>numeric</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
> for floating-point arguments,
otherwise <TT
CLASS="TYPE"
>numeric</TT
>
</TD
><TD
>sample standard deviation of the input values</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>variance</CODE
>(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)
</TD
><TD
> <TT
CLASS="TYPE"
>smallint</TT
>, <TT
CLASS="TYPE"
>int</TT
>,
<TT
CLASS="TYPE"
>bigint</TT
>, <TT
CLASS="TYPE"
>real</TT
>, <TT
CLASS="TYPE"
>double
precision</TT
>, or <TT
CLASS="TYPE"
>numeric</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
> for floating-point arguments,
otherwise <TT
CLASS="TYPE"
>numeric</TT
>
</TD
><TD
>historical alias for <CODE
CLASS="FUNCTION"
>var_samp</CODE
></TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>var_pop</CODE
>(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)
</TD
><TD
> <TT
CLASS="TYPE"
>smallint</TT
>, <TT
CLASS="TYPE"
>int</TT
>,
<TT
CLASS="TYPE"
>bigint</TT
>, <TT
CLASS="TYPE"
>real</TT
>, <TT
CLASS="TYPE"
>double
precision</TT
>, or <TT
CLASS="TYPE"
>numeric</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
> for floating-point arguments,
otherwise <TT
CLASS="TYPE"
>numeric</TT
>
</TD
><TD
>population variance of the input values (square of the population standard deviation)</TD
></TR
><TR
><TD
>
<CODE
CLASS="FUNCTION"
>var_samp</CODE
>(<TT
CLASS="REPLACEABLE"
><I
>expression</I
></TT
>)
</TD
><TD
> <TT
CLASS="TYPE"
>smallint</TT
>, <TT
CLASS="TYPE"
>int</TT
>,
<TT
CLASS="TYPE"
>bigint</TT
>, <TT
CLASS="TYPE"
>real</TT
>, <TT
CLASS="TYPE"
>double
precision</TT
>, or <TT
CLASS="TYPE"
>numeric</TT
>
</TD
><TD
> <TT
CLASS="TYPE"
>double precision</TT
> for floating-point arguments,
otherwise <TT
CLASS="TYPE"
>numeric</TT
>
</TD
><TD
>sample variance of the input values (square of the sample standard deviation)</TD
></TR
></TBODY
></TABLE
></DIV
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="functions-range.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="functions-window.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Range Functions and Operators</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="functions.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Window Functions</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>