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Random copy-editing.

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This commit is contained in:
Peter Eisentraut
2003-11-04 09:55:39 +00:00
parent c119c554ed
commit 1d27de4cf4
21 changed files with 571 additions and 588 deletions
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63
doc/src/sgml/array.sgml
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@@ -1,4 +1,4 @@
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/array.sgml,v 1.32 2003/11/01 01:56:28 petere Exp $ -->
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/array.sgml,v 1.33 2003/11/04 09:55:38 petere Exp $ -->
<sect1 id="arrays">
<title>Arrays</title>
@@ -76,13 +76,45 @@ CREATE TABLE tictactoe (
<sect2>
<title>Array Value Input</title>
<para>
Now we can show some <command>INSERT</command> statements. To write an array
value as a literal constant, we enclose the element values within curly
braces and separate them by commas. (If you know C, this is not unlike the
C syntax for initializing structures.) We may put double quotes around any
element value, and must do so if it contains commas or curly braces.
(More details appear below.)
<indexterm>
<primary>array</primary>
<secondary>constant</secondary>
</indexterm>
<para>
To write an array value as a literal constant, enclose the element
values within curly braces and separate them by commas. (If you
know C, this is not unlike the C syntax for initializing
structures.) You may put double quotes around any element value,
and must do so if it contains commas or curly braces. (More
details appear below.) Thus, the general format of an array
constant is the following:
<synopsis>
'{ <replaceable>val1</replaceable> <replaceable>delim</replaceable> <replaceable>val2</replaceable> <replaceable>delim</replaceable> ... }'
</synopsis>
where <replaceable>delim</replaceable> is the delimiter character
for the type, as recorded in its <literal>pg_type</literal> entry.
(For all built-in types, this is the comma character
<quote><literal>,</literal></>.) Each
<replaceable>val</replaceable> is either a constant of the array
element type, or a subarray. An example of an array constant is
<programlisting>
'{{1,2,3},{4,5,6},{7,8,9}}'
</programlisting>
This constant is a two-dimensional, 3-by-3 array consisting of
three subarrays of integers.
</para>
<para>
(These kinds of array constants are actually only a special case of
the generic type constants discussed in <xref
linkend="sql-syntax-constants-generic">. The constant is initially
treated as a string and passed to the array input conversion
routine. An explicit type specification might be necessary.)
</para>
<para>
Now we can show some <command>INSERT</command> statements.
<programlisting>
INSERT INTO sal_emp
@@ -95,14 +127,15 @@ INSERT INTO sal_emp
'{20000, 25000, 25000, 25000}',
'{{"talk", "consult"}, {"meeting"}}');
</programlisting>
</para>
</para>
<para>
A limitation of the present array implementation is that individual
elements of an array cannot be SQL null values. The entire array
can be set to null, but you can't have an array with some elements
null and some not.
</para>
<para>
A limitation of the present array implementation is that individual
elements of an array cannot be SQL null values. The entire array can be set
to null, but you can't have an array with some elements null and some
not.
</para>
<para>
This can lead to surprising results. For example, the result of the
previous two inserts looks like this: