psql-ref.sgml

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

      <varlistentry>
        <term><literal>\dT [ <replaceable class="parameter">pattern</replaceable> ]</literal></term>
        <term><literal>\dT+ [ <replaceable class="parameter">pattern</replaceable> ]</literal></term>
        <listitem>
        <para>
        Lists all data types or only those that match <replaceable
        class="parameter">pattern</replaceable>. The command form
        <literal>\dT+</literal> shows extra information.
        </para>
        </listitem>
      </varlistentry>


      <varlistentry>
        <term><literal>\du [ <replaceable class="parameter">pattern</replaceable> ]</literal></term>
        <listitem>
        <para>
        Lists all database roles, or only those that match <replaceable
        class="parameter">pattern</replaceable>.
        </para>
        </listitem>
      </varlistentry>


      <varlistentry>
        <term><literal>\edit</literal> (or <literal>\e</literal>) <literal>[ <replaceable class="parameter">filename</replaceable> ]</literal></term>

        <listitem>
        <para>
        If <replaceable class="parameter">filename</replaceable> is
        specified, the file is edited; after the editor exits, its
        content is copied back to the query buffer. If no argument is
        given, the current query buffer is copied to a temporary file
        which is then edited in the same fashion.
        </para>

        <para>
        The new query buffer is then re-parsed according to the normal
        rules of <application>psql</application>, where the whole buffer
        is treated as a single line. (Thus you cannot make scripts this
        way. Use <command>\i</command> for that.) This means also that
        if the query ends with (or rather contains) a semicolon, it is
        immediately executed. In other cases it will merely wait in the
        query buffer.
        </para>

        <tip>
        <para>
        <application>psql</application> searches the environment
        variables <envar>PSQL_EDITOR</envar>, <envar>EDITOR</envar>, and
        <envar>VISUAL</envar> (in that order) for an editor to use. If
        all of them are unset, <filename>vi</filename> is used on Unix
        systems, <filename>notepad.exe</filename> on Windows systems.
        </para>
        </tip>
        </listitem>
      </varlistentry>


      <varlistentry>
        <term><literal>\echo <replaceable class="parameter">text</replaceable> [ ... ]</literal></term>
        <listitem>
        <para>
        Prints the arguments to the standard output, separated by one
        space and followed by a newline. This can be useful to
        intersperse information in the output of scripts. For example:
<programlisting>
=&gt; <userinput>\echo `date`</userinput>
Tue Oct 26 21:40:57 CEST 1999
</programlisting>
        If the first argument is an unquoted <literal>-n</literal> the trailing
        newline is not written.
        </para>

        <tip>
        <para>
        If you use the <command>\o</command> command to redirect your
        query output you may wish to use <command>\qecho</command>
        instead of this command.
        </para>
        </tip>
        </listitem>
      </varlistentry>


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

        <listitem>
        <para>
        Sets the client character set encoding.  Without an argument, this command
        shows the current encoding.
        </para>
        </listitem>
      </varlistentry>


      <varlistentry>
        <term><literal>\f [ <replaceable class="parameter">string</replaceable> ]</literal></term>

        <listitem>
        <para>
        Sets the field separator for unaligned query output. The default
        is the vertical bar (<literal>|</literal>). See also
        <command>\pset</command> for a generic way of setting output
        options.
        </para>
        </listitem>
      </varlistentry>


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

        <listitem>
        <para>
        Sends the current query input buffer to the server and
        optionally stores the query's output in <replaceable
        class="parameter">filename</replaceable> or pipes the output
        into a separate Unix shell executing <replaceable
        class="parameter">command</replaceable>. A bare
        <literal>\g</literal> is virtually equivalent to a semicolon. A
        <literal>\g</literal> with argument is a <quote>one-shot</quote>
        alternative to the <command>\o</command> command.
        </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>\help</literal> (or <literal>\h</literal>) <literal>[ <replaceable class="parameter">command</replaceable> ]</literal></term>
        <listitem>
        <para>
        Gives syntax help on the specified <acronym>SQL</acronym>
        command. If <replaceable class="parameter">command</replaceable>
        is not specified, then <application>psql</application> will list
        all the commands for which syntax help is available. If
        <replaceable class="parameter">command</replaceable> is an
        asterisk (<literal>*</literal>), then syntax help on all
        <acronym>SQL</acronym> commands is shown.
        </para>

        <note>
        <para>
        To simplify typing, commands that consists of several words do
        not have to be quoted. Thus it is fine to type <userinput>\help
        alter table</userinput>.
        </para>
        </note>
        </listitem>
      </varlistentry>


      <varlistentry>
        <term><literal>\H</literal></term>
        <listitem>
        <para>
        Turns on <acronym>HTML</acronym> query output format. If the
        <acronym>HTML</acronym> format is already on, it is switched
        back to the default aligned text format. This command is for
        compatibility and convenience, but see <command>\pset</command>
        about setting other output options.
        </para>
        </listitem>
      </varlistentry>


      <varlistentry>
        <term><literal>\i <replaceable class="parameter">filename</replaceable></literal></term>
        <listitem>
        <para>
        Reads input from the file <replaceable
        class="parameter">filename</replaceable> and executes it as
        though it had been typed on the keyboard.
        </para>
        <note>
        <para>
        If you want to see the lines on the screen as they are read you
        must set the variable <varname>ECHO</varname> to
        <literal>all</literal>.
        </para>
        </note>
        </listitem>
      </varlistentry>


      <varlistentry>
        <term><literal>\l</literal> (or <literal>\list</literal>)</term>
        <term><literal>\l+</literal> (or <literal>\list+</literal>)</term>
        <listitem>
        <para>
        List the names, owners, and character set encodings of all the databases in
        the server. If <literal>+</literal> is appended to the command
        name, database descriptions are also displayed.
        </para>
        </listitem>
      </varlistentry>


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

        <listitem>
        <para>
        Reads the large object with <acronym>OID</acronym> <replaceable
        class="parameter">loid</replaceable> from the database and
        writes it to <replaceable
        class="parameter">filename</replaceable>. Note that this is
        subtly different from the server function
        <function>lo_export</function>, which acts with the permissions
        of the user that the database server runs as and on the server's
        file system.
        </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>\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 one ought to remember if one wants to access the
        object ever again. For that reason it is recommended to always
        associate a human-readable comment with every object. Those can
        then be seen 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>\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).