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Add support for dividing money by money (yielding a float8 result) and for

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casting between money and numeric.

Andy Balholm, reviewed by Kevin Grittner
This commit is contained in:
Tom Lane
2010-07-16 02:15:56 +00:00
parent e11cfa87be
commit 7590ddb3eb
7 changed files with 148 additions and 34 deletions
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54
doc/src/sgml/datatype.sgml
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@@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.250 2010/07/03 04:03:06 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.251 2010/07/16 02:15:53 tgl Exp $ -->
<chapter id="datatype">
<title>Data Types</title>
@@ -839,32 +839,11 @@ ALTER SEQUENCE <replaceable class="parameter">tablename</replaceable>_<replaceab
fractional precision; see <xref
linkend="datatype-money-table">. The fractional precision is
determined by the database's <xref linkend="guc-lc-monetary"> setting.
The range shown in the table assumes there are two fractional digits.
Input is accepted in a variety of formats, including integer and
floating-point literals, as well as typical
currency formatting, such as <literal>'$1,000.00'</literal>.
Output is generally in the latter form but depends on the locale.
Non-quoted numeric values can be converted to <type>money</type> by
casting the numeric value to <type>text</type> and then
<type>money</type>, for example:
<programlisting>
SELECT 1234::text::money;
</programlisting>
There is no simple way of doing the reverse in a locale-independent
manner, namely casting a <type>money</type> value to a numeric type.
If you know the currency symbol and thousands separator you can use
<function>regexp_replace()</>:
<programlisting>
SELECT regexp_replace('52093.89'::money::text, '[$,]', '', 'g')::numeric;
</programlisting>
</para>
<para>
Since the output of this data type is locale-sensitive, it might not
work to load <type>money</> data into a database that has a different
setting of <varname>lc_monetary</>. To avoid problems, before
restoring a dump into a new database make sure <varname>lc_monetary</> has the same or
equivalent value as in the database that was dumped.
</para>
<table id="datatype-money-table">
@@ -888,6 +867,35 @@ SELECT regexp_replace('52093.89'::money::text, '[$,]', '', 'g')::numeric;
</tbody>
</tgroup>
</table>
<para>
Since the output of this data type is locale-sensitive, it might not
work to load <type>money</> data into a database that has a different
setting of <varname>lc_monetary</>. To avoid problems, before
restoring a dump into a new database make sure <varname>lc_monetary</> has
the same or equivalent value as in the database that was dumped.
</para>
<para>
Values of the <type>numeric</type> data type can be cast to
<type>money</type>. Other numeric types can be converted to
<type>money</type> by casting to <type>numeric</type> first, for example:
<programlisting>
SELECT 1234::numeric::money;
</programlisting>
A <type>money</type> value can be cast to <type>numeric</type> without
loss of precision. Conversion to other types could potentially lose
precision, and it must be done in two stages, for example:
<programlisting>
SELECT '52093.89'::money::numeric::float8;
</programlisting>
</para>
<para>
When a <type>money</type> value is divided by another <type>money</type>
value, the result is <type>double precision</type> (i.e., a pure number,
not money); the currency units cancel each other out in the division.
</para>
</sect1>