From 175dbf741bde1eb13eafc309a2c719569b778397 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 30 Mar 2000 23:42:34 +0000
Subject: [PATCH] Make discussion of names clearer and more accurate.
---
doc/src/sgml/syntax.sgml | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/doc/src/sgml/syntax.sgml b/doc/src/sgml/syntax.sgml
index 918d91a05cf..30f57e5ccf6 100644
--- a/doc/src/sgml/syntax.sgml
+++ b/doc/src/sgml/syntax.sgml
@@ -340,17 +340,23 @@ A comment beginning with "/*" extends to the first occurrence of "*/".
<title>Names</title>
<para>
- Names in SQL are sequences of less than NAMEDATALEN alphanumeric characters,
- starting with an alphabetic character. By default, NAMEDATALEN is set
- to 32 (but at the time the system is built, NAMEDATALEN can be changed
- by changing the <literal>#define</literal> in
- src/backend/include/postgres.h).
- Underscore ("_") is considered an alphabetic character.
+ Names in SQL must begin with a letter
+ (<literal>a</literal>-<literal>z</literal>) or underscore
+ (<literal>_</literal>).
+ Subsequent characters in a name can be letters, digits
+ (<literal>0</literal>-<literal>9</literal>),
+ or underscores. The system uses no more than NAMEDATALEN-1 characters
+ of a name; longer names can be written in queries, but they will be
+ truncated.
+ By default, NAMEDATALEN is 32 so the maximum name length is 31 (but
+ at the time the system is built, NAMEDATALEN can be changed in
+ src/include/postgres_ext.h).
</para>
<para>
Names containing other characters may be formed by surrounding them
- with double quotes. For example, table or column names may contain
+ with double quotes (<literal>"</literal>). For example, table or column
+ names may contain
otherwise disallowed characters such as spaces, ampersands, etc. if
quoted. Quoting a name also makes it case-sensitive,
whereas unquoted names are always folded to lower case. For example,
@@ -359,6 +365,12 @@ A comment beginning with "/*" extends to the first occurrence of "*/".
considered the same by <productname>Postgres</productname>, but
<literal>"Foo"</literal> is a different name.
</para>
+
+ <para>
+ Double quotes can also be used to protect a name that would otherwise
+ be taken to be an SQL keyword. For example, <literal>IN</literal>
+ is a keyword but <literal>"IN"</literal> is a name.
+ </para>
</sect1>
<sect1>
--
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