<replaceable>fields</replaceable> must include <literal>SECOND</literal>,
    since the precision applies only to the seconds.
   </para>

   <para>
    The type <type>time with time zone</type> is defined by the SQL
    standard, but the definition exhibits properties which lead to
    questionable usefulness. In most cases, a combination of
    <type>date</type>, <type>time</type>, <type>timestamp without time
    zone</type>, and <type>timestamp with time zone</type> should
    provide a complete range of date/time functionality required by
    any application.
   </para>

   <sect2 id="datatype-datetime-input">
    <title>Date/Time Input</title>

    <para>
     Date and time input is accepted in almost any reasonable format, including
     ISO 8601, <acronym>SQL</acronym>-compatible,
     traditional <productname>POSTGRES</productname>, and others.
     For some formats, ordering of day, month, and year in date input is
     ambiguous and there is support for specifying the expected
     ordering of these fields.  Set the <xref linkend="guc-datestyle"/> parameter
     to <literal>MDY</literal> to select month-day-year interpretation,
     <literal>DMY</literal> to select day-month-year interpretation, or
     <literal>YMD</literal> to select year-month-day interpretation.
    </para>

    <para>
     <productname>PostgreSQL</productname> is more flexible in
     handling date/time input than the
     <acronym>SQL</acronym> standard requires.
     See <xref linkend="datetime-appendix"/>
     for the exact parsing rules of date/time input and for the
     recognized text fields including months, days of the week, and
     time zones.
    </para>

    <para>
     Remember that any date or time literal input needs to be enclosed
     in single quotes, like text strings.  Refer to
     <xref linkend="sql-syntax-constants-generic"/> for more
     information.
     <acronym>SQL</acronym> requires the following syntax
<synopsis>
<replaceable>type</replaceable> [ (<replaceable>p</replaceable>) ] '<replaceable>value</replaceable>'
</synopsis>
     where <replaceable>p</replaceable> is an optional precision
     specification giving the number of
     fractional digits in the seconds field. Precision can be
     specified for <type>time</type>, <type>timestamp</type>, and
     <type>interval</type> types, and can range from 0 to 6.
     If no precision is specified in a constant specification,
     it defaults to the precision of the literal value (but not
     more than 6 digits).
    </para>

    <sect3 id="datatype-datetime-input-dates">
    <title>Dates</title>

    <indexterm>
     <primary>date</primary>
    </indexterm>

    <para>
     <xref linkend="datatype-datetime-date-table"/> shows some possible
     inputs for the <type>date</type> type.
    </para>

     <table id="datatype-datetime-date-table">
      <title>Date Input</title>
      <tgroup cols="2">
       <colspec colname="col1" colwidth="1*"/>
       <colspec colname="col2" colwidth="2*"/>
       <thead>
        <row>
         <entry>Example</entry>
         <entry>Description</entry>
        </row>
       </thead>
       <tbody>
        <row>
         <entry>1999-01-08</entry>
         <entry>ISO 8601; January 8 in any mode
         (recommended format)</entry>
        </row>
        <row>
         <entry>January 8, 1999</entry>
         <entry>unambiguous in any <varname>datestyle</varname> input mode</entry>
        </row>
        <row>
         <entry>1/8/1999</entry>
         <entry>January 8 in <literal>MDY</literal> mode;
          August 1 in <literal>DMY</literal> mode</entry>
        </row>
        <row>
         <entry>1/18/1999</entry>
         <entry>January 18 in <literal>MDY</literal> mode;
          rejected in other modes</entry>
        </row>
        <row>
         <entry>01/02/03</entry>
         <entry>January 2, 2003 in <literal>MDY</literal> mode;
          February 1, 2003 in <literal>DMY</literal> mode;
          February 3, 2001 in <literal>YMD</literal>