which has an offset of +10:00 hours from UTC.

</para>

</note>

</para>

<para>

Australian time zones and their naming variants

</ListItem>

</VarListEntry>

</VariableList>

</Para>

</sect1>

<Sect1>

<filename>src/libpq++/examples</filename>, including the source

code for the three examples in this chapter.

</para>

<sect1>

<title>Control and Initialization</title>

<para>

</para>

<sect2>

<title>Environment Variables</title>

</Para>

</sect2>

</sect1>

<sect1>

<title>Database Connection Functions</title>

<para>

</para>

<sect2>

<title>Database Environment Class: <classname>PGenv</classname></title>

</para>

</sect2>

</sect1>

<sect1>

<title>Query Execution Functions</title>

</itemizedlist>

</para>

</sect1>

<sect1>

<title>Asynchronous Notification</title>

notification.

</para>

</sect1>

<sect1>

<title>Functions Associated with the COPY Command</title>

</programlisting>

</para>

</sect1>

<sect1>

<title>Caveats</title>

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Postgres integrated documentation.

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Revision 1.20 1999/04/06 15:41:13 thomas

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<synopsis>

[ CONSTRAINT name ] NULL

</synopsis>

</para>

</REFSECT3>

<REFSECT3 ID="R3-SQL-NOTNULL-4">

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<command>DISTINCT ON <replaceable class="PARAMETER">column</replaceable></command> will eliminate all duplicates in the specified column; this is

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including duplicates.

including duplicates.</para>

<para>

The GROUP BY clause allows a user to divide a table

conceptually into groups. (See GROUP BY clause).</para>

<chapter id="syntax">

<chapter>

<title>SQL Syntax</title>

<sect1>

<firstterm>not restricted</firstterm>, which indicates that in certain

contexts they

have a specific meaning but are not otherwise constrained.

</para>

<para>

<productname>Postgres</productname> implements an extended subset of the

<acronym>SQL92</acronym> and <acronym>SQL3</acronym> languages. Some language

elements are not as restricted in this implementation as is

called for in the language standards, in part due

to the extensibility features of <productname>Postgres</productname>.

</para>

<para>

Information on <acronym>SQL92</acronym> and <acronym>SQL3</acronym> key words

is derived from <xref linkend="DATE97" endterm="DATE97-full">.

is derived from <xref linkend="DATE97" endterm="DATE97">.

</para>

<Sect2>

<Title>Reserved Key Words</Title>

<sect2>

<title>Reserved Key Words</title>

<Para>

<para>

<acronym>SQL92</acronym> and <acronym>SQL3</acronym> have

<firstterm>reserved key words</firstterm> which are not allowed

as identifiers and not allowed in any usage other than as fundamental

which have similar restrictions. In particular, these key words

are not allowed as column or table names, though in some cases

they are allowed to be column labels (i.e. in AS clauses).

</para>

<tip>

<para>

Any string can be specified as an identifier if surrounded by

double quotes (<quote>like this!</quote>). Some care is required since

such an identifier will be case sensitive

and will retain embedded whitespace other special characters.

and will retain embedded whitespace other special characters.</para>

</tip>

<para>

UNLISTEN UNTIL

VACUUM VERBOSE

</programlisting>

</para>

<para>

The following are <productname>Postgres</productname>

reserved words which are also <acronym>SQL92</acronym>

or <acronym>SQL3</acronym> reserved words, and which

VALUES VARCHAR VARYING VIEW

WHERE WITH WORK

</programlisting>

</para>

<para>

The following are <acronym>SQL92</acronym> reserved key words which

are not <productname>Postgres</productname> reserved key words, but which

if used as function names are always translated into the function

<programlisting>

CHAR_LENGTH CHARACTER_LENGTH

</programlisting>

</para>

<para>

The following are <acronym>SQL92</acronym> or <acronym>SQL3</acronym>

reserved key words which

are not <productname>Postgres</productname> reserved key words, but

<programlisting>

BOOLEAN DOUBLE FLOAT INT INTEGER INTERVAL REAL SMALLINT

</programlisting>

</para>

<para>

The following are either <acronym>SQL92</acronym>

These functions are defined in <productname>Postgres</productname>,

but the parser does not consider the names to be key words and they are allowed

in other contexts.

</para>

</note>

<programlisting>

VALUE

WHENEVER WRITE

</programlisting>

</para>

</sect2>

<Sect2>

<Title>Non-reserved Keywords</Title>

<sect2>

<title>Non-reserved Keywords</title>

<Para>

<para>

<acronym>SQL92</acronym> and <acronym>SQL3</acronym> have

<firstterm>non-reserved keywords</firstterm> which have

a proscribed meaning in the language but which are also allowed

which allow similar unrestricted usage.

In particular, these keywords

are allowed as column or table names.

</para>

<para>

The following are <productname>Postgres</productname>

TRUSTED

VALID VERSION

</programlisting>

</para>

<para>

The following are <productname>Postgres</productname>

YEAR

ZONE

</programlisting>

</para>

<para>

The following are <productname>Postgres</productname>

<programlisting>

TYPE

</programlisting>

</para>

<para>

The following are either <acronym>SQL92</acronym>

TABLE_NAME

UNCOMMITTED UNNAMED

</programlisting>

</para>

</sect2>

</sect1>

</chapter>

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