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c5f42daa60
- Misc grammar and punctuation fixes. - Stylistic cleanup: use spaces between function arguments and JSON fields in examples. For example "foo(a,b)" -> "foo(a, b)". Add semicolon after last END in a few PL/pgSQL examples that were missing them. - Make sentence that talked about "..." and ".." operators more clear, by avoiding to end the sentence with "..". That makes it look the same as "..." - Fix syntax description for HAVING: HAVING conditions cannot be repeated Patch by Justin Pryzby, per Yaroslav Schekin's report. Backpatch to all supported versions, to the extent that the patch applies easily. Discussion: https://www.postgresql.org/message-id/20201005191922.GE17626%40telsasoft.com
425 lines
12 KiB
Plaintext
425 lines
12 KiB
Plaintext
<!-- doc/src/sgml/isn.sgml -->
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<sect1 id="isn" xreflabel="isn">
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<title>isn</title>
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<indexterm zone="isn">
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<primary>isn</primary>
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</indexterm>
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<para>
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The <filename>isn</filename> module provides data types for the following
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international product numbering standards: EAN13, UPC, ISBN (books), ISMN
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(music), and ISSN (serials). Numbers are validated on input according to a
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hard-coded list of prefixes; this list of prefixes is also used to hyphenate
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numbers on output. Since new prefixes are assigned from time to time, the
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list of prefixes may be out of date. It is hoped that a future version of
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this module will obtain the prefix list from one or more tables that
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can be easily updated by users as needed; however, at present, the
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list can only be updated by modifying the source code and recompiling.
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Alternatively, prefix validation and hyphenation support may be
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dropped from a future version of this module.
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</para>
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<para>
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This module is considered <quote>trusted</quote>, that is, it can be
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installed by non-superusers who have <literal>CREATE</literal> privilege
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on the current database.
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</para>
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<sect2>
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<title>Data Types</title>
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<para>
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<xref linkend="isn-datatypes"/> shows the data types provided by
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the <filename>isn</filename> module.
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</para>
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<table id="isn-datatypes">
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<title><filename>isn</filename> Data Types</title>
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<tgroup cols="2">
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<colspec colname="col1" colwidth="1*"/>
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<colspec colname="col2" colwidth="2*"/>
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<thead>
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<row>
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<entry>Data Type</entry>
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<entry>Description</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><type>EAN13</type></entry>
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<entry>
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European Article Numbers, always displayed in the EAN13 display format
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</entry>
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</row>
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<row>
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<entry><type>ISBN13</type></entry>
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<entry>
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International Standard Book Numbers to be displayed in
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the new EAN13 display format
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</entry>
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</row>
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<row>
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<entry><type>ISMN13</type></entry>
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<entry>
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International Standard Music Numbers to be displayed in
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the new EAN13 display format
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</entry>
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</row>
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<row>
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<entry><type>ISSN13</type></entry>
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<entry>
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International Standard Serial Numbers to be displayed in the new
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EAN13 display format
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</entry>
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</row>
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<row>
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<entry><type>ISBN</type></entry>
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<entry>
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International Standard Book Numbers to be displayed in the old
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short display format
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</entry>
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</row>
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<row>
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<entry><type>ISMN</type></entry>
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<entry>
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International Standard Music Numbers to be displayed in the
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old short display format
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</entry>
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</row>
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<row>
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<entry><type>ISSN</type></entry>
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<entry>
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International Standard Serial Numbers to be displayed in the
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old short display format
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</entry>
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</row>
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<row>
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<entry><type>UPC</type></entry>
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<entry>
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Universal Product Codes
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</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<para>
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Some notes:
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</para>
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<orderedlist>
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<listitem>
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<para>ISBN13, ISMN13, ISSN13 numbers are all EAN13 numbers.</para>
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</listitem>
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<listitem>
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<para>EAN13 numbers aren't always ISBN13, ISMN13 or ISSN13 (some
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are).</para>
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</listitem>
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<listitem>
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<para>Some ISBN13 numbers can be displayed as ISBN.</para>
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</listitem>
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<listitem>
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<para>Some ISMN13 numbers can be displayed as ISMN.</para>
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</listitem>
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<listitem>
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<para>Some ISSN13 numbers can be displayed as ISSN.</para>
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</listitem>
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<listitem>
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<para>UPC numbers are a subset of the EAN13 numbers (they are basically
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EAN13 without the first <literal>0</literal> digit).</para>
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</listitem>
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<listitem>
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<para>All UPC, ISBN, ISMN and ISSN numbers can be represented as EAN13
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numbers.</para>
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</listitem>
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</orderedlist>
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<para>
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Internally, all these types use the same representation (a 64-bit
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integer), and all are interchangeable. Multiple types are provided
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to control display formatting and to permit tighter validity checking
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of input that is supposed to denote one particular type of number.
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</para>
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<para>
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The <type>ISBN</type>, <type>ISMN</type>, and <type>ISSN</type> types will display the
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short version of the number (ISxN 10) whenever it's possible, and will show
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ISxN 13 format for numbers that do not fit in the short version.
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The <type>EAN13</type>, <type>ISBN13</type>, <type>ISMN13</type> and
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<type>ISSN13</type> types will always display the long version of the ISxN
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(EAN13).
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</para>
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</sect2>
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<sect2>
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<title>Casts</title>
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<para>
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The <filename>isn</filename> module provides the following pairs of type casts:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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ISBN13 <=> EAN13
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</para>
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</listitem>
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<listitem>
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<para>
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ISMN13 <=> EAN13
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</para>
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</listitem>
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<listitem>
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<para>
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ISSN13 <=> EAN13
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</para>
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</listitem>
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<listitem>
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<para>
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ISBN <=> EAN13
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</para>
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</listitem>
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<listitem>
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<para>
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ISMN <=> EAN13
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</para>
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</listitem>
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<listitem>
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<para>
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ISSN <=> EAN13
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</para>
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</listitem>
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<listitem>
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<para>
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UPC <=> EAN13
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</para>
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</listitem>
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<listitem>
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<para>
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ISBN <=> ISBN13
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</para>
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</listitem>
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<listitem>
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<para>
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ISMN <=> ISMN13
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</para>
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</listitem>
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<listitem>
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<para>
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ISSN <=> ISSN13
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</para>
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</listitem>
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</itemizedlist>
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<para>
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When casting from <type>EAN13</type> to another type, there is a run-time
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check that the value is within the domain of the other type, and an error
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is thrown if not. The other casts are simply relabelings that will
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always succeed.
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</para>
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</sect2>
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<sect2>
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<title>Functions and Operators</title>
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<para>
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The <filename>isn</filename> module provides the standard comparison operators,
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plus B-tree and hash indexing support for all these data types. In
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addition there are several specialized functions; shown in <xref linkend="isn-functions"/>.
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In this table,
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<type>isn</type> means any one of the module's data types.
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</para>
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<table id="isn-functions">
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<title><filename>isn</filename> Functions</title>
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<tgroup cols="1">
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<thead>
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<row>
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<entry role="func_table_entry"><para role="func_signature">
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Function
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</para>
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<para>
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Description
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</para></entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry role="func_table_entry"><para role="func_signature">
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<indexterm><primary>isn_weak</primary></indexterm>
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<function>isn_weak</function> ( <type>boolean</type> )
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<returnvalue>boolean</returnvalue>
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</para>
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<para>
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Sets the weak input mode, and returns new setting.
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</para></entry>
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</row>
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<row>
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<entry role="func_table_entry"><para role="func_signature">
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<function>isn_weak</function> ()
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<returnvalue>boolean</returnvalue>
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</para>
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<para>
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Returns the current status of the weak mode.
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</para></entry>
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</row>
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<row>
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<entry role="func_table_entry"><para role="func_signature">
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<indexterm><primary>make_valid</primary></indexterm>
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<function>make_valid</function> ( <type>isn</type> )
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<returnvalue>isn</returnvalue>
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</para>
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<para>
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Validates an invalid number (clears the invalid flag).
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</para></entry>
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</row>
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<row>
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<entry role="func_table_entry"><para role="func_signature">
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<indexterm><primary>is_valid</primary></indexterm>
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<function>is_valid</function> ( <type>isn</type> )
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<returnvalue>boolean</returnvalue>
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</para>
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<para>
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Checks for the presence of the invalid flag.
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</para></entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<para>
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<firstterm>Weak</firstterm> mode is used to be able to insert invalid data
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into a table. Invalid means the check digit is wrong, not that there are
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missing numbers.
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</para>
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<para>
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Why would you want to use the weak mode? Well, it could be that
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you have a huge collection of ISBN numbers, and that there are so many of
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them that for weird reasons some have the wrong check digit (perhaps the
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numbers were scanned from a printed list and the OCR got the numbers wrong,
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perhaps the numbers were manually captured... who knows). Anyway, the point
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is you might want to clean the mess up, but you still want to be able to
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have all the numbers in your database and maybe use an external tool to
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locate the invalid numbers in the database so you can verify the
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information and validate it more easily; so for example you'd want to
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select all the invalid numbers in the table.
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</para>
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<para>
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When you insert invalid numbers in a table using the weak mode, the number
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will be inserted with the corrected check digit, but it will be displayed
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with an exclamation mark (<literal>!</literal>) at the end, for example
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<literal>0-11-000322-5!</literal>. This invalid marker can be checked with
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the <function>is_valid</function> function and cleared with the
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<function>make_valid</function> function.
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</para>
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<para>
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You can also force the insertion of invalid numbers even when not in the
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weak mode, by appending the <literal>!</literal> character at the end of the
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number.
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</para>
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<para>
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Another special feature is that during input, you can write
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<literal>?</literal> in place of the check digit, and the correct check digit
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will be inserted automatically.
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</para>
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</sect2>
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<sect2>
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<title>Examples</title>
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<programlisting>
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--Using the types directly:
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SELECT isbn('978-0-393-04002-9');
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SELECT isbn13('0901690546');
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SELECT issn('1436-4522');
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--Casting types:
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-- note that you can only cast from ean13 to another type when the
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-- number would be valid in the realm of the target type;
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-- thus, the following will NOT work: select isbn(ean13('0220356483481'));
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-- but these will:
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SELECT upc(ean13('0220356483481'));
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SELECT ean13(upc('220356483481'));
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--Create a table with a single column to hold ISBN numbers:
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CREATE TABLE test (id isbn);
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INSERT INTO test VALUES('9780393040029');
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--Automatically calculate check digits (observe the '?'):
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INSERT INTO test VALUES('220500896?');
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INSERT INTO test VALUES('978055215372?');
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SELECT issn('3251231?');
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SELECT ismn('979047213542?');
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--Using the weak mode:
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SELECT isn_weak(true);
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INSERT INTO test VALUES('978-0-11-000533-4');
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INSERT INTO test VALUES('9780141219307');
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INSERT INTO test VALUES('2-205-00876-X');
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SELECT isn_weak(false);
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SELECT id FROM test WHERE NOT is_valid(id);
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UPDATE test SET id = make_valid(id) WHERE id = '2-205-00876-X!';
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SELECT * FROM test;
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SELECT isbn13(id) FROM test;
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</programlisting>
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</sect2>
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<sect2>
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<title>Bibliography</title>
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<para>
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The information to implement this module was collected from
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several sites, including:
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<itemizedlist>
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<listitem><para><ulink url="https://www.isbn-international.org/"></ulink></para></listitem>
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<listitem><para><ulink url="https://www.issn.org/"></ulink></para></listitem>
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<listitem><para><ulink url="https://www.ismn-international.org/"></ulink></para></listitem>
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<listitem><para><ulink url="https://www.wikipedia.org/"></ulink></para></listitem>
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</itemizedlist>
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The prefixes used for hyphenation were also compiled from:
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<itemizedlist>
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<listitem><para><ulink url="https://www.gs1.org/standards/id-keys"></ulink></para></listitem>
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<listitem><para><ulink url="https://en.wikipedia.org/wiki/List_of_ISBN_identifier_groups"></ulink></para></listitem>
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<listitem><para><ulink url="https://www.isbn-international.org/content/isbn-users-manual"></ulink></para></listitem>
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<listitem><para><ulink url="https://en.wikipedia.org/wiki/International_Standard_Music_Number"></ulink></para></listitem>
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<listitem><para><ulink url="https://www.ismn-international.org/ranges.html"></ulink></para></listitem>
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</itemizedlist>
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Care was taken during the creation of the algorithms and they
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were meticulously verified against the suggested algorithms
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in the official ISBN, ISMN, ISSN User Manuals.
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</para>
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</sect2>
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<sect2>
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<title>Author</title>
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<para>
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Germán Méndez Bravo (Kronuz), 2004–2006
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</para>
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<para>
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This module was inspired by Garrett A. Wollman's
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<filename>isbn_issn</filename> code.
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</para>
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</sect2>
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</sect1>
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