Add CSV table output mode in psql.

"\pset format csv", or --csv, selects comma-separated values table format.
This is compliant with RFC 4180, except that we aren't too picky about
whether the record separator is LF or CRLF; also, the user may choose a
field separator other than comma.

This output format is directly compatible with the server's COPY CSV
format, and will also be useful as input to other programs.  It's
considerably safer for that purpose than the old recommendation to
use "unaligned" format, since the latter couldn't handle data
containing the field separator character.

Daniel Vérité, reviewed by Fabien Coelho and David Fetter, some
tweaking by me

Discussion: https://postgr.es/m/a8de371e-006f-4f92-ab72-2bbe3ee78f03@manitou-mail.org

doc/src/sgml/ref/psql-ref.sgml

@@ -68,8 +68,8 @@ PostgreSQL documentation
       <listitem>
       <para>
       Switches to unaligned output mode. (The default output mode is
-      otherwise aligned.)  This is equivalent to <command>\pset format
-      unaligned</command>.
+      <literal>aligned</literal>.)  This is equivalent to
+      <command>\pset format unaligned</command>.
       </para>
       </listitem>
     </varlistentry>
@@ -151,6 +151,16 @@ EOF
       </listitem>
     </varlistentry>
 
+    <varlistentry>
+      <term><option>--csv</option></term>
+      <listitem>
+      <para>
+      Switches to <acronym>CSV</acronym> (Comma-Separated Values) output
+      mode.  This is equivalent to <command>\pset format csv</command>.
+      </para>
+      </listitem>
+    </varlistentry>
+
     <varlistentry>
       <term><option>-d <replaceable class="parameter">dbname</replaceable></option></term>
       <term><option>--dbname=<replaceable class="parameter">dbname</replaceable></option></term>
@@ -270,8 +280,8 @@ EOF
       <term><option>--html</option></term>
       <listitem>
       <para>
-      Turn on <acronym>HTML</acronym> tabular output. This is
-      equivalent to <literal>\pset format html</literal> or the
+      Switches to <acronym>HTML</acronym> output mode.  This is
+      equivalent to <command>\pset format html</command> or the
       <command>\H</command> command.
       </para>
       </listitem>
@@ -2520,6 +2530,19 @@ lo_import 152801
           </listitem>
           </varlistentry>
 
+          <varlistentry>
+          <term><literal>csv_fieldsep</literal></term>
+          <listitem>
+          <para>
+          Specifies the field separator to be used in
+          <acronym>CSV</acronym> output format.  If the separator character
+          appears in a field's value, that field is output within double
+          quotes, following standard <acronym>CSV</acronym> rules.
+          The default is a comma.
+          </para>
+          </listitem>
+          </varlistentry>
+
           <varlistentry>
           <term><literal>expanded</literal> (or <literal>x</literal>)</term>
           <listitem>
@@ -2547,8 +2570,8 @@ lo_import 152801
           <listitem>
           <para>
           Specifies the field separator to be used in unaligned output
-          format. That way one can create, for example, tab- or
-          comma-separated output, which other programs might prefer. To
+          format. That way one can create, for example, tab-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).
@@ -2585,22 +2608,48 @@ lo_import 152801
           <listitem>
           <para>
           Sets the output format to one of <literal>aligned</literal>,
-          <literal>asciidoc</literal>, <literal>html</literal>,
-          <literal>latex</literal> (uses <literal>tabular</literal>),
+          <literal>asciidoc</literal>,
+          <literal>csv</literal>,
+          <literal>html</literal>,
+          <literal>latex</literal>,
           <literal>latex-longtable</literal>, <literal>troff-ms</literal>,
           <literal>unaligned</literal>, or <literal>wrapped</literal>.
           Unique abbreviations are allowed.
           </para>
 
+          <para><literal>aligned</literal> format is the standard,
+          human-readable, nicely formatted text output; this is the default.
+          </para>
+
           <para><literal>unaligned</literal> format writes all columns of a row on one
           line, separated by the currently active field separator. This
           is useful for creating output that might be intended to be read
-          in by other programs (for example, tab-separated or comma-separated
-          format).
+          in by other programs, for example, tab-separated or comma-separated
+          format.  However, the field separator character is not treated
+          specially if it appears in a column's value;
+          so <acronym>CSV</acronym> format may be better suited for such
+          purposes.
           </para>
 
-          <para><literal>aligned</literal> format is the standard, human-readable,
-          nicely formatted text output;  this is the default.
+          <para><literal>csv</literal> format
+          <indexterm>
+           <primary>CSV (Comma-Separated Values) format</primary>
+           <secondary>in psql</secondary>
+          </indexterm>
+          writes column values separated by commas, applying the quoting
+          rules described in
+          <ulink url="https://tools.ietf.org/html/rfc4180">RFC 4180</ulink>.
+          This output is compatible with the CSV format of the server's
+          <command>COPY</command> command.
+          A header line with column names is generated unless
+          the <literal>tuples_only</literal> parameter is
+          <literal>on</literal>. Titles and footers are not printed.
+          Each row is terminated by the system-dependent end-of-line character,
+          which is typically a single newline (<literal>\n</literal>) for
+          Unix-like systems or a carriage return and newline sequence
+          (<literal>\r\n</literal>) for Microsoft Windows.
+          Field separator characters other than comma can be selected with
+          <command>\pset csv_fieldsep</command>.
           </para>
 
           <para><literal>wrapped</literal> format is like <literal>aligned</literal> but wraps
@@ -2620,8 +2669,12 @@ lo_import 152801
           language. They are not complete documents! This might not be
           necessary in <acronym>HTML</acronym>, but in
           <application>LaTeX</application> you must have a complete
-          document wrapper.  <literal>latex-longtable</literal>
-          also requires the <application>LaTeX</application>
+          document wrapper.
+          The <literal>latex</literal> format
+          uses <application>LaTeX</application>'s <literal>tabular</literal>
+          environment.
+          The <literal>latex-longtable</literal> format
+          requires the <application>LaTeX</application>
           <literal>longtable</literal> and <literal>booktabs</literal> packages.
           </para>
           </listitem>
@@ -4588,17 +4641,24 @@ first second
 
 peter@localhost testdb=&gt; <userinput>\pset border 1</userinput>
 Border style is 1.
-peter@localhost testdb=&gt; <userinput>\pset format unaligned</userinput>
-Output format is unaligned.
-peter@localhost testdb=&gt; <userinput>\pset fieldsep ","</userinput>
-Field separator is ",".
+peter@localhost testdb=&gt; <userinput>\pset format csv</userinput>
+Output format is csv.
 peter@localhost testdb=&gt; <userinput>\pset tuples_only</userinput>
-Showing only tuples.
+Tuples only is on.
 peter@localhost testdb=&gt; <userinput>SELECT second, first FROM my_table;</userinput>
 one,1
 two,2
 three,3
 four,4
+peter@localhost testdb=&gt; <userinput>\pset format unaligned</userinput>
+Output format is unaligned.
+peter@localhost testdb=&gt; <userinput>\pset fieldsep '\t'</userinput>
+Field separator is "    ".
+peter@localhost testdb=&gt; <userinput>SELECT second, first FROM my_table;</userinput>
+one     1
+two     2
+three   3
+four    4
 </programlisting>
   Alternatively, use the short commands:
 <programlisting>