psql-ref.sgml

postgresql8.3.4源码,开源数据库

        <tip>
        <para>
        Use <command>\lo_list</command> to find out the large object's
        <acronym>OID</acronym>.
        </para>
        </tip>
        </listitem>
      </varlistentry>


      <varlistentry>
        <term><literal>\lo_import <replaceable class="parameter">filename</replaceable> [ <replaceable class="parameter">comment</replaceable> ]</literal></term>

        <listitem>
        <para>
        Stores the file into a <productname>PostgreSQL</productname>
        large object. Optionally, it associates the given
        comment with the object. Example:
<programlisting>
foo=&gt; <userinput>\lo_import '/home/peter/pictures/photo.xcf' 'a picture of me'</userinput>
lo_import 152801
</programlisting>
        The response indicates that the large object received object
        ID 152801, which can be used to access the newly-created large
        object in the future. For the sake of readability, it is
        recommended to always associate a human-readable comment with
        every object. Both OIDs and comments can be viewed with the
        <command>\lo_list</command> command.
        </para>

        <para>
        Note that this command is subtly different from the server-side
        <function>lo_import</function> because it acts as the local user
        on the local file system, rather than the server's user and file
        system.
        </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>\lo_list</literal></term>
        <listitem>
        <para>
        Shows a list of all <productname>PostgreSQL</productname>
        large objects currently stored in the database,
        along with any comments provided for them.
        </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>\lo_unlink <replaceable class="parameter">loid</replaceable></literal></term>

        <listitem>
        <para>
        Deletes the large object with <acronym>OID</acronym>
        <replaceable class="parameter">loid</replaceable> from the
        database.
        </para>

        <tip>
        <para>
        Use <command>\lo_list</command> to find out the large object's
        <acronym>OID</acronym>.
        </para>
        </tip>
        </listitem>
      </varlistentry>


      <varlistentry>
        <term><literal>\o</literal> [ {<replaceable class="parameter">filename</replaceable> | <literal>|</literal><replaceable class="parameter">command</replaceable>} ]</term>

        <listitem>
        <para>
        Saves future query results to the file <replaceable
        class="parameter">filename</replaceable> or pipes future results
        into a separate Unix shell to execute <replaceable
        class="parameter">command</replaceable>. If no arguments are
        specified, the query output will be reset to the standard output.
        </para>

        <para>
        <quote>Query results</quote> includes all tables, command
        responses, and notices obtained from the database server, as
        well as output of various backslash commands that query the
        database (such as <command>\d</command>), but not error
        messages.
        </para>

        <tip>
        <para>
        To intersperse text output in between query results, use
        <command>\qecho</command>.
        </para>
        </tip>
        </listitem>
      </varlistentry>


      <varlistentry>
        <term><literal>\p</literal></term>
        <listitem>
        <para>
        Print the current query buffer to the standard output.
        </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>\password [ <replaceable class="parameter">username</replaceable> ]</literal></term>
        <listitem>
        <para>
        Changes the password of the specified user (by default, the current
        user).  This command prompts for the new password, encrypts it, and
        sends it to the server as an <command>ALTER ROLE</> command.  This
        makes sure that the new password does not appear in cleartext in the
        command history, the server log, or elsewhere.
        </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>\prompt [ <replaceable class="parameter">text</replaceable> ] <replaceable class="parameter">name</replaceable></literal></term>
        <listitem>
        <para>
         Prompts the user to set variable <replaceable
         class="parameter">name</>.  An optional prompt, <replaceable
         class="parameter">text</>, can be specified.  (For multi-word
         prompts, use single-quotes.)
        </para>

        <para>
         By default, <literal>\prompt</> uses the terminal for input and
         output.  However, if the <option>-f</> command line switch is
         used, <literal>\prompt</> uses standard input and standard output.
        </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>\pset <replaceable class="parameter">parameter</replaceable> [ <replaceable class="parameter">value</replaceable> ]</literal></term>

        <listitem>
        <para>
        This command sets options affecting the output of query result
        tables. <replaceable class="parameter">parameter</replaceable>
        describes which option is to be set. The semantics of
        <replaceable class="parameter">value</replaceable> depend
        thereon.
        </para>

        <para>
        Adjustable printing options are:
        <variablelist>
          <varlistentry>
          <term><literal>format</literal></term>
          <listitem>
          <para>
          Sets the output format to one of <literal>unaligned</literal>,
          <literal>aligned</literal>, <literal>html</literal>,
          <literal>latex</literal>, or <literal>troff-ms</literal>.
          Unique abbreviations are allowed.  (That would mean one letter
          is enough.)
          </para>

          <para>
          <quote>Unaligned</quote> writes all columns of a row on a
          line, separated by the currently active field separator. This
          is intended to create output that might be intended to be read
          in by other programs (tab-separated, comma-separated).
          <quote>Aligned</quote> mode is the standard, human-readable,
          nicely formatted text output that is default. The
          <quote><acronym>HTML</acronym></quote> and
          <quote>LaTeX</quote> modes put out tables that are intended to
          be included in documents using the respective mark-up
          language. They are not complete documents! (This might not be
          so dramatic in <acronym>HTML</acronym>, but in LaTeX you must
          have a complete document wrapper.)
          </para>
          </listitem>
          </varlistentry>

          <varlistentry>
          <term><literal>border</literal></term>
          <listitem>
          <para>
          The second argument must be a number. In general, the higher
          the number the more borders and lines the tables will have,
          but this depends on the particular format. In
          <acronym>HTML</acronym> mode, this will translate directly
          into the <literal>border=...</literal> attribute, in the
          others only values 0 (no border), 1 (internal dividing lines),
          and 2 (table frame) make sense.
          </para>
          </listitem>
          </varlistentry>

          <varlistentry>
          <term><literal>expanded</literal> (or <literal>x</literal>)</term>
          <listitem>
          <para>
          You can specify an optional second argument, if it is provided it
          may be either <literal>on</literal> or <literal>off</literal>
          which will enable or disable expanded mode.  If the second
          argument is not provided then we will toggle between regular and
          expanded format. When expanded format is enabled, query results
          are displayed in two columns, with the column name on the left and
          the data on the right. This mode is useful if the data wouldn't fit
          on the screen in the normal <quote>horizontal</quote> mode.
          </para>

          <para>
          Expanded mode is supported by all four output formats.
          </para>
          </listitem>
          </varlistentry>

          <varlistentry>
          <term><literal>null</literal></term>
          <listitem>
          <para>
          The second argument is a string that should be printed
          whenever a column is null. The default is not to print
          anything, which can easily be mistaken for, say, an empty
          string. Thus, one might choose to write <literal>\pset null
          '(null)'</literal>.
          </para>
          </listitem>
          </varlistentry>

          <varlistentry>
          <term><literal>fieldsep</literal></term>
          <listitem>
          <para>
          Specifies the field separator to be used in unaligned output
          mode. That way one can create, for example, tab- or
          comma-separated output, which other programs might prefer. To
          set a tab as field separator, type <literal>\pset fieldsep
          '\t'</literal>. The default field separator is
          <literal>'|'</literal> (a vertical bar).
          </para>
          </listitem>
          </varlistentry>

          <varlistentry>
          <term><literal>footer</literal></term>
          <listitem>
          <para>
          You can specify an optional second argument, if it is provided it
          may be either <literal>on</literal> or <literal>off</literal>
          which will enable or disable display of the default footer
          <literal>(x rows)</literal>.  If the second argument is not
          provided then we will toggle between on and off.
          </para>
          </listitem>
          </varlistentry>

          <varlistentry>
          <term><literal>numericlocale</literal></term>
          <listitem>
          <para>
          You can specify an optional second argument, if it is provided it
          may be either <literal>on</literal> or <literal>off</literal>
          which will enable or disable display of a locale-aware character
          to seperate groups of digits to the left of the decimal marker.  If
          the second argument is not provided then we will toggle between
          on and off.
          </para>
          </listitem>
          </varlistentry>

          <varlistentry>
          <term><literal>recordsep</literal></term>
          <listitem>
          <para>
          Specifies the record (line) separator to use in unaligned
          output mode. The default is a newline character.
          </para>
          </listitem>
          </varlistentry>

          <varlistentry>
          <term><literal>tuples_only</literal> (or <literal>t</literal>)</term>
          <listitem>
          <para>
          You can specify an optional second argument, if it is provided it
          may be either <literal>on</literal> or <literal>off</literal>
          which will enable or disable the tuples only mode.  If the
          second argument is not provided then we will toggle between tuples
          only and full display. Full display shows extra information such
          as column headers, titles, and various footers. In tuples only
          mode, only actual table data is shown.
          </para>
          </listitem>
          </varlistentry>

          <varlistentry>
          <term><literal>title [ <replaceable class="parameter">text</replaceable> ]</literal></term>
          <listitem>
          <para>
          Sets the table title for any subsequently printed tables. This
          can be used to give your output descriptive tags. If no
          argument is given, the title is unset.
          </para>
          </listitem>
          </varlistentry>

          <varlistentry>
          <term><literal>tableattr</literal> (or <literal>T</literal>) <literal>[ <replaceable class="parameter">text</replaceable> ]</literal></term>
          <listitem>
          <para>
          Allows you to specify any attributes to be placed inside the
          <acronym>HTML</acronym> <sgmltag>table</sgmltag> tag. This
          could for example be <literal>cellpadding</literal> or
          <literal>bgcolor</literal>. Note that you probably don't want
          to specify <literal>border</literal> here, as that is already
          taken care of by <literal>\pset border</literal>.
          </para>
          </listitem>
          </varlistentry>


          <varlistentry>
          <term><literal>pager</literal></term>
          <listitem>
          <para>
          Controls use of a pager for query and <application>psql</>
          help output. If the environment variable <envar>PAGER</envar>
          is set, the output is piped to the specified program.
          Otherwise a platform-dependent default (such as
          <filename>more</filename>) is used.
          </para>

          <para>
          When the pager is off, the pager is not used. When the pager
          is on, the pager is used only when appropriate, i.e. the