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postgresql8.4-docs-8.4.12-0.1mdv2010.2.i586.rpm

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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="FUNCTIONS-AGGREGATE"
>9.18. Aggregate Functions</A
></H1
><A
NAME="AEN15649"
></A
><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 9-42</A
> and
   <A
HREF="functions-aggregate.html#FUNCTIONS-AGGREGATE-STATISTICS-TABLE"
>Table 9-43</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 9-42. General-Purpose Aggregate Functions</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
>       <A
NAME="AEN15670"
></A
>
       <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 concatenated into an array</TD
></TR
><TR
><TD
>       <A
NAME="AEN15679"
></A
>
       <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
>       <A
NAME="AEN15697"
></A
>
       <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
>       <A
NAME="AEN15710"
></A
>
       <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
>       <A
NAME="AEN15723"
></A
>
       <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
>       <A
NAME="AEN15734"
></A
>
       <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
>&nbsp;</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
>       <A
NAME="AEN15761"
></A
>
       <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"
>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
>, or
       <TT
CLASS="TYPE"
>interval</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, <TT
CLASS="TYPE"
>double precision</TT
>
       for floating-point 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
>       <A
NAME="AEN15810"
></A
>
       <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"
><A
NAME="AEN15826"
></A
><A
NAME="AEN15828"
></A
><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 sub-select
      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 be executed by <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> using a
    sequential scan of the entire table.
   </P
></BLOCKQUOTE
></DIV
><P
>   The aggregate functions <CODE
CLASS="FUNCTION"
>array_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.  In the current
   implementation, the order of the input is in principle unspecified.
   Supplying the input values from a sorted subquery
   will usually work, however.  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.  A future version of
   <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> might provide an additional feature to control
   the order in a better-defined way (<TT
CLASS="LITERAL"
>xmlagg(expr ORDER BY expr, expr,
   ...)</TT
>).
  </P
><P
>   <A
HREF="functions-aggregate.html#FUNCTIONS-AGGREGATE-STATISTICS-TABLE"
>Table 9-43</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
><A
NAME="AEN15855"
></A
><A
NAME="AEN15857"
></A
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-AGGREGATE-STATISTICS-TABLE"
></A
><P
><B
>Table 9-43. 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
>       <A
NAME="AEN15871"
></A
>
       <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
>       <A
NAME="AEN15883"
></A
>
       <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
>       <A
NAME="AEN15896"
></A
>
       <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
>       <A
NAME="AEN15945"
></A
>
       <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
>       <A
NAME="AEN15969"
></A
>
       <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
>       <A
NAME="AEN16030"
></A
>
       <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
>       <A
NAME="AEN16048"
></A
>
       <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
>       <A
NAME="AEN16066"
></A
>
       <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
>       <A
NAME="AEN16084"
></A
>
       <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
>       <A
NAME="AEN16102"
></A
>
       <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
>       <A
NAME="AEN16120"
></A
>
       <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
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