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$PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.99 2004/12/23 05:37:40 tgl Exp $

$PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.100 2005/06/02 01:23:08 momjian Exp $

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<chapter id="sql-syntax">

<para>

Another <productname>PostgreSQL</productname> extension is that

C-style backslash escapes are available:

<literal>\b</literal> is a backspace, <literal>\f</literal> is a

form feed, <literal>\n</literal> is a newline,

<literal>\r</literal> is a carriage return, <literal>\t</literal>

is a tab, and <literal>\<replaceable>xxx</replaceable></literal>,

where <replaceable>xxx</replaceable> is an octal number, is a

byte with the corresponding code. (It is your responsibility

that the byte sequences you create are valid characters in the

server character set encoding.) Any other character following a

backslash is taken literally. Thus, to include a backslash in a

string constant, write two backslashes.

C-style backslash escapes are available: <literal>\b</literal> is a

backspace, <literal>\f</literal> is a form feed,

<literal>\n</literal> is a newline, <literal>\r</literal> is a

carriage return, <literal>\t</literal> is a tab. Also supported is

<literal>\<replaceable>digits</replaceable></literal>, where

<replaceable>ddd</replaceable> represents an octal byte value, and

<literal>\x<replaceable>hexdigits</replaceable></literal>, where

<replaceable>hexdigits</replaceable> represents a hexadecimal byte value.

(It is your responsibility that the byte sequences you create are

valid characters in the server character set encoding.) Any other

character following a backslash is taken literally. Thus, to

include a backslash in a string constant, write two backslashes.

</para>

<para>

xqstart{quote}

xqdouble{quote}{quote}

xqinside[^\\']+

xqescape[\\][^0-7]

xqescape[\\][^0-7x]

xqoctesc[\\][0-7]{1,3}

xqhexesc[\\]x[0-9A-Fa-f]{1,2}

unsignedchar c =strtoul(yytext+1,NULL,8);

addlitchar(c);

}

<xq>{xqhexesc} {

unsignedchar c =strtoul(yytext+2,NULL,16);

addlitchar(c);

}

<xq>{quotecontinue} {

}