Update array slice documentation to be clearer.

This commit is contained in:
Bruce Momjian 2007-02-20 14:34:25 +00:00
parent 265124e7e0
commit 1b52359d90
1 changed files with 7 additions and 11 deletions

View File

@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/array.sgml,v 1.56 2007/02/01 00:28:16 momjian Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/array.sgml,v 1.57 2007/02/20 14:34:25 momjian Exp $ -->
<sect1 id="arrays">
<title>Arrays</title>
@ -243,18 +243,14 @@ SELECT schedule[1:2][1:1] FROM sal_emp WHERE name = 'Bill';
(1 row)
</programlisting>
We could also have written:
If any dimmension is written as a slice, i.e contains a colon, then all
dimmensions are treated as slices. If a dimmension is missing, it is
assumed to be <literal>[1:1]</>. If a dimmension has only a single
number (no colon), that dimmension is treated as being from <literal>1</>
to the number specified. For example, <literal>[2]</> is treated as
<literal>[1:2], as in this example:
<programlisting>
SELECT schedule[1:2][1] FROM sal_emp WHERE name = 'Bill';
</programlisting>
with the same result. An array subscripting operation is always taken to
represent an array slice if any of the subscripts are written in the form
<literal><replaceable>lower</replaceable>:<replaceable>upper</replaceable></literal>.
A lower bound of 1 is assumed for any subscript where only one value
is specified, as in this example:
<programlisting>
SELECT schedule[1:2][2] FROM sal_emp WHERE name = 'Bill';
schedule