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Update documentation for backslashes to mention escape string syntax

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more, and standard_conforming_strings less, because in the future non-E
strings will not treat backslashes specially.

Also use E'' strings where backslashes are used in examples. (The
existing examples would have drawn warnings.)

Backpatch to 8.2.X.
This commit is contained in:
Bruce Momjian
2007-01-30 22:29:23 +00:00
parent 35b039a26c
commit 4ed9f1d9b7
9 changed files with 82 additions and 87 deletions
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18
doc/src/sgml/array.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/array.sgml,v 1.52 2006/09/29 21:22:21 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/array.sgml,v 1.53 2007/01/30 22:29:22 momjian Exp $ -->
<sect1 id="arrays">
<title>Arrays</title>
@ -597,17 +597,17 @@ SELECT f1[1][-2][3] AS e1, f1[1][-1][5] AS e2
</para>
<para>
As shown previously, when writing an array value you may write double
As shown previously, when writing an array value you can write double
quotes around any individual array element. You <emphasis>must</> do so
if the element value would otherwise confuse the array-value parser.
For example, elements containing curly braces, commas (or whatever the
delimiter character is), double quotes, backslashes, or leading or trailing
whitespace must be double-quoted. Empty strings and strings matching the
word <literal>NULL</> must be quoted, too. To put a double quote or
backslash in a
quoted array element value, precede it with a backslash. Alternatively, you
can use backslash-escaping to protect all data characters that would
otherwise be taken as array syntax.
backslash in a quoted array element value, use escape string syntax
and precede it with a backslash. Alternatively, you can use
backslash-escaping to protect all data characters that would otherwise
be taken as array syntax.
</para>
<para>
@ -625,16 +625,16 @@ SELECT f1[1][-2][3] AS e1, f1[1][-1][5] AS e2
backslashes you need. For example, to insert a <type>text</> array
value containing a backslash and a double quote, you'd need to write
<programlisting>
INSERT ... VALUES ('{"\\\\","\\""}');
INSERT ... VALUES (E'{"\\\\","\\""}');
</programlisting>
The string-literal processor removes one level of backslashes, so that
The escape string processor removes one level of backslashes, so that
what arrives at the array-value parser looks like <literal>{"\\","\""}</>.
In turn, the strings fed to the <type>text</> data type's input routine
become <literal>\</> and <literal>"</> respectively. (If we were working
with a data type whose input routine also treated backslashes specially,
<type>bytea</> for example, we might need as many as eight backslashes
in the command to get one backslash into the stored array element.)
Dollar quoting (see <xref linkend="sql-syntax-dollar-quoting">) may be
Dollar quoting (see <xref linkend="sql-syntax-dollar-quoting">) can be
used to avoid the need to double backslashes.
</para>
</note>