diff options
| -rw-r--r-- | doc/src/sgml/func.sgml | 81 | ||||
| -rw-r--r-- | doc/src/sgml/sql.sgml | 4 | ||||
| -rw-r--r-- | doc/src/sgml/syntax.sgml | 4 |
3 files changed, 85 insertions, 4 deletions
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 3b50375e160..0023a28b0aa 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -1515,6 +1515,87 @@ Not defined by this name. Implements the intersection operator '#' </sect1> + <sect1> + + <title id="aggregate-funcs">Aggregate Functions</title> + + <note> + <title>Author</title> + <para> + Written by <ulink url="mailto:isaac@azartmedia.com">Isaac Wilcox</ulink> + on 2000-06-16. + </para> + </note> + + <para> + <firstterm>Aggregate functions</firstterm> allow the generation of simple + statistics about the values of particular columns over the selected set + of rows. See also <xref linkend="sql" endterm="aggregates-tutorial"> and + <xref linkend="syntax" endterm="aggregates-syntax">. + </para> + + <para> + <table tocentry="1"> + <title>Aggregate Functions</title> + <tgroup cols="4"> + <thead> + <row> + <entry>Function</entry> + <entry>Returns</entry> + <entry>Description</entry> + <entry>Example</entry> + <entry>Notes</entry> + </row> + </thead> + <tbody> + <row> + <entry>COUNT(*)</entry> + <entry>int4</entry> + <entry>Counts the selected rows.</entry> + <entry>COUNT(*)</entry> + <entry></entry> + </row> + <row> + <entry>COUNT(<replaceable class="parameter">column-name</replaceable>)</entry> + <entry>int4</entry> + <entry>Counts the selected rows for which the value of <replaceable class="parameter">column-name</replaceable> is not NULL.</entry> + <entry>COUNT(age)</entry> + <entry></entry> + </row> + <row> + <entry>SUM(<replaceable class="parameter">column-name</replaceable>)</entry> + <entry>Same as the data type of the column being summed.</entry> + <entry>Finds the total obtained by adding the values of <replaceable class="parameter">column-name</replaceable> across all selected rows.</entry> + <entry>SUM(hours)</entry> + <entry>Summation is supported on the following data types: int8, int4, int2, float4, float8, money, interval, numeric</entry> + </row> + <row> + <entry>MAX(<replaceable class="parameter">column-name</replaceable>)</entry> + <entry>Same as the data type of the column whose maximum value is sought.</entry> + <entry>The maximum value of <replaceable class="parameter">column-name</replaceable> across all selected rows.</entry> + <entry>MAX(age)</entry> + <entry>Finding the maximum value is supported on the following data types: int8, int4, int2, float4, float8, date, time, timetz, money, timestamp, interval, text, numeric.</entry> + </row> + <row> + <entry>MIN(<replaceable class="parameter">column-name</replaceable>)</entry> + <entry>same as the data type of the column whose minimum value is sought.</entry> + <entry>The minimum value of <replaceable class="parameter">column-name</replaceable> across all selected rows.</entry> + <entry>MIN(age)</entry> + <entry>Finding the minimum value is supported on the following data types: int8, int4, int2, float4, float8, date, time, timetz, money, timestamp, interval, text, numeric.</entry> + </row> + <row> + <entry>AVG(<replaceable class="parameter">column-name</replaceable>)</entry> + <entry>Same as the data type of the column being averaged.</entry> + <entry>The average (mean) of the values in the given column across all selected rows.</entry> + <entry>AVG(age)</entry> + <entry>Finding the mean value is supported on the following data types: int8, int4, int2, float4, float8, money, interval, numeric. Note that as the return type is the same as that of the data being averaged, using AVG() on discrete data will give a rounded result.</entry> + </row> + </tbody> + </tgroup> + </table> + </para> + </sect1> + </chapter> <!-- Keep this comment at the end of the file diff --git a/doc/src/sgml/sql.sgml b/doc/src/sgml/sql.sgml index 054b2fba730..05d6442fbb0 100644 --- a/doc/src/sgml/sql.sgml +++ b/doc/src/sgml/sql.sgml @@ -1,5 +1,5 @@ <!-- -$Header: /cvsroot/pgsql/doc/src/sgml/sql.sgml,v 1.10 2000/06/14 13:10:48 thomas Exp $ +$Header: /cvsroot/pgsql/doc/src/sgml/sql.sgml,v 1.11 2000/06/20 18:04:18 momjian Exp $ --> <chapter id="sql"> @@ -1032,7 +1032,7 @@ SELECT S.SNAME, P.PNAME </sect3> <sect3> - <title>Aggregate Operators</title> + <title id="aggregates-tutorial">Aggregate Operators</title> <para> <acronym>SQL</acronym> provides aggregate operators diff --git a/doc/src/sgml/syntax.sgml b/doc/src/sgml/syntax.sgml index f07da189173..6c9ccaf45e5 100644 --- a/doc/src/sgml/syntax.sgml +++ b/doc/src/sgml/syntax.sgml @@ -1,5 +1,5 @@ <!-- -$Header: /cvsroot/pgsql/doc/src/sgml/syntax.sgml,v 1.21 2000/06/09 01:43:56 momjian Exp $ +$Header: /cvsroot/pgsql/doc/src/sgml/syntax.sgml,v 1.22 2000/06/20 18:04:18 momjian Exp $ --> <chapter id="syntax"> @@ -747,7 +747,7 @@ sqrt(emp.salary) </sect2> <sect2> - <title>Aggregate Expressions</title> + <title id="aggregates-syntax">Aggregate Expressions</title> <para> An <firstterm>aggregate expression</firstterm> represents the application |