Add information about bit types. Adjust some other things to promote
SQL type names over internal type names.
This commit is contained in:
Peter Eisentraut
parent
475c1452b1
commit
526427f6d3
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@ -1,17 +1,10 @@
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<!--
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$Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.46 2000/12/22 18:57:49 petere Exp $
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$Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.47 2001/01/13 18:34:51 petere Exp $
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-->
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<chapter id="datatype">
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<title id="datatype-title">Data Types</title>
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<abstract>
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<para>
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Describes the built-in data types available in
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<productname>Postgres</productname>.
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</para>
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</abstract>
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<para>
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<productname>Postgres</productname> has a rich set of native data
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types available to users.
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@ -20,229 +13,229 @@ $Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.46 2000/12/22 18:57:49 pe
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</para>
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<para>
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In the context of data types, the following sections will discuss
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<acronym>SQL</acronym> standards compliance, porting issues, and usage.
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Some <productname>Postgres</productname> types correspond directly to
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<acronym>SQL92</acronym>-compatible types. In other
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cases, data types defined by <acronym>SQL92</acronym> syntax are mapped directly
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into native <productname>Postgres</productname> types.
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Many of the built-in types have obvious external formats. However, several
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types are either unique to <productname>Postgres</productname>,
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such as open and closed paths, or have
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several possibilities for formats, such as the date and time types.
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<xref linkend="datatype-table"> shows all general-purpose data types
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available to users. Most of the alternative names listed in the
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<quote>Aliases</quote> column are the names used internally by
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<productname>Postgres</productname> for historical reasons. In
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addition, some internally used or deprecated types are available,
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but they are not documented here. Many of the built-in types have
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obvious external formats. However, several types are either unique
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to <productname>Postgres</productname>, such as open and closed
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paths, or have several possibilities for formats, such as the date
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and time types.
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</para>
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<para>
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<table tocentry="1">
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<table id="datatype-table">
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<title><productname>Postgres</productname> Data Types</title>
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<titleabbrev>Data Types</titleabbrev>
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<tgroup cols="3">
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<thead>
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<row>
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<entry><productname>Postgres</productname> Type</entry>
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<entry><acronym>SQL92</acronym> or <acronym>SQL99</acronym> Type</entry>
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<entry>Type Name</entry>
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<entry>Aliases</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>bool</entry>
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<entry>boolean</entry>
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<entry><type>bigint</type></entry>
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<entry><type>int8</type></entry>
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<entry>signed eight-byte integer</entry>
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</row>
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<row>
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<entry><type>bit</type></entry>
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<entry></entry>
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<entry>fixed-length bit string</entry>
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</row>
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<row>
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<entry><type>bit varying(<replaceable>n</replaceable>)</type></entry>
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<entry><type>varbit(<replaceable>n</replaceable>)</type></entry>
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<entry>variable-length bit string</entry>
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</row>
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<row>
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<entry><type>boolean</type></entry>
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<entry><type>bool</type></entry>
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<entry>logical boolean (true/false)</entry>
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</row>
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<row>
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<entry>box</entry>
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<entry><type>box</type></entry>
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<entry></entry>
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<entry>rectangular box in 2D plane</entry>
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</row>
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<row>
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<entry>char(n)</entry>
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<entry>character(n)</entry>
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<entry><type>character(<replaceable>n</replaceable>)</type></entry>
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<entry><type>char(<replaceable>n</replaceable>)</type></entry>
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<entry>fixed-length character string</entry>
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</row>
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<row>
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<entry>cidr</entry>
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<entry><type>character varying(<replaceable>n</replaceable>)</type></entry>
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<entry><type>varchar(<replaceable>n</replaceable>)</type></entry>
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<entry>variable-length character string</entry>
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</row>
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<row>
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<entry><type>cidr</type></entry>
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<entry></entry>
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<entry>IP network address</entry>
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</row>
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<row>
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<entry>circle</entry>
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<entry><type>circle</type></entry>
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<entry></entry>
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<entry>circle in 2D plane</entry>
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</row>
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<row>
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<entry>date</entry>
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<entry>date</entry>
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<entry>calendar date without time of day</entry>
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</row>
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<row>
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<entry>decimal</entry>
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<entry>decimal(p,s)</entry>
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<entry>exact numeric with selectable precision</entry>
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</row>
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<row>
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<entry>float4</entry>
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<entry>float(<replaceable>p</replaceable>), <replaceable>p</replaceable> < 7</entry>
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<entry>floating-point number with precision <replaceable>p</replaceable></entry>
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</row>
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<row>
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<entry>float8</entry>
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<entry>float(<replaceable>p</replaceable>), 7 <= <replaceable>p</replaceable> < 16</entry>
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<entry>floating-point number with precision <replaceable>p</replaceable></entry>
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</row>
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<row>
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<entry>inet</entry>
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<entry><type>date</type></entry>
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<entry></entry>
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<entry>IP network or host address</entry>
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<entry>calendar date (year, month, day)</entry>
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</row>
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<row>
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<entry>int2</entry>
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<entry>smallint</entry>
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<entry>signed two-byte integer</entry>
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<entry><type>double precision</type></entry>
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<entry><type>float8</type></entry>
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<entry>double precision floating-point number</entry>
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</row>
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<row>
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<entry>int4</entry>
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<entry>int, integer</entry>
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<entry>signed 4-byte integer</entry>
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</row>
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<row>
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<entry>int8</entry>
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<entry><type>inet</type></entry>
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<entry></entry>
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<entry>signed 8-byte integer</entry>
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<entry>IP host address</entry>
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</row>
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<row>
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<entry>interval</entry>
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<entry>interval</entry>
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<entry><type>integer</type></entry>
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<entry><type>int</type>, <type>int4</type></entry>
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<entry>signed four-byte integer</entry>
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</row>
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<row>
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<entry><type>interval</type></entry>
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<entry></entry>
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<entry>general-use time span</entry>
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</row>
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<row>
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<entry>line</entry>
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<entry><type>line</type></entry>
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<entry></entry>
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<entry>infinite line in 2D plane</entry>
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</row>
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<row>
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<entry>lseg</entry>
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<entry><type>lseg</type></entry>
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<entry></entry>
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<entry>line segment in 2D plane</entry>
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</row>
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<row>
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<entry>money</entry>
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<entry>decimal(9,2)</entry>
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<entry><type>macaddr</type></entry>
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<entry></entry>
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<entry>MAC address</entry>
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</row>
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<row>
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<entry><type>money</type></entry>
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<entry></entry>
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<entry>US-style currency</entry>
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</row>
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<row>
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<entry>numeric</entry>
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<entry>numeric(p,s)</entry>
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<entry><type>numeric(<replaceable>p</replaceable>, <replaceable>s</replaceable>)</type></entry>
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<entry><type>decimal(<replaceable>p</replaceable>, <replaceable>s</replaceable>)</type></entry>
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<entry>exact numeric with selectable precision</entry>
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</row>
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<row>
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<entry>path</entry>
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<entry><type>oid</type></entry>
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<entry></entry>
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<entry>object identifier</entry>
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</row>
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<row>
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<entry><type>path</type></entry>
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<entry></entry>
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<entry>open and closed geometric path in 2D plane</entry>
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</row>
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<row>
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<entry>point</entry>
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<entry><type>point</type></entry>
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<entry></entry>
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<entry>geometric point in 2D plane</entry>
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</row>
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<row>
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<entry>polygon</entry>
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<entry><type>polygon</type></entry>
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<entry></entry>
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<entry>closed geometric path in 2D plane</entry>
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</row>
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<row>
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<entry>serial</entry>
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<entry></entry>
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<entry>unique id for indexing and cross-reference</entry>
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<entry><type>real</type></entry>
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<entry><type>float4</type></entry>
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<entry>single precision floating-point number</entry>
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</row>
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<row>
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<entry>text</entry>
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<entry><type>smallint</type></entry>
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<entry><type>int2</type></entry>
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<entry>signed two-byte integer</entry>
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</row>
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<row>
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<entry><type>serial</type></entry>
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<entry></entry>
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<entry>autoincrementing four-byte integer</entry>
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</row>
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<row>
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<entry><type>text</type></entry>
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<entry></entry>
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<entry>variable-length character string</entry>
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</row>
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<row>
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<entry>time</entry>
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<entry>time [ without time zone ]</entry>
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<entry><type>time [ without time zone ]</type></entry>
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<entry></entry>
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<entry>time of day</entry>
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</row>
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<row>
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<entry>timetz</entry>
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<entry>time with time zone</entry>
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<entry><type>time with time zone</type></entry>
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<entry></entry>
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<entry>time of day, including time zone</entry>
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</row>
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<row>
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<entry>timestamp</entry>
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<entry>timestamp [ with time zone ]</entry>
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<entry>date/time</entry>
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</row>
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<row>
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<entry>varchar(n)</entry>
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<entry>character varying(n)</entry>
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<entry>variable-length character string</entry>
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<entry><type>timestamp [ with time zone ]</type></entry>
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<entry></entry>
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<entry>date and time</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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<para>
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<note>
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<para>
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The <type>cidr</type> and <type>inet</type> types are designed to handle any IP type
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but only ipv4 is handled in the current implementation.
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Everything here that talks about ipv4 will apply to ipv6 in a
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future release.
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</para>
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</note>
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</para>
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<para>
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<table tocentry="1">
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<title><productname>Postgres</productname> Function Constants</title>
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<titleabbrev>Constants</titleabbrev>
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<tgroup cols="3">
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<thead>
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<row>
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<entry><productname>Postgres</productname> Function</entry>
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<entry><acronym>SQL92</acronym> Constant</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>date('now')</entry>
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<entry>current_date</entry>
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<entry>date of current transaction</entry>
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</row>
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<row>
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<entry>time('now')</entry>
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<entry>current_time</entry>
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<entry>time of current transaction</entry>
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</row>
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<row>
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<entry>timestamp('now')</entry>
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<entry>current_timestamp</entry>
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<entry>date and time of current transaction</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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<para>
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<productname>Postgres</productname> has features at the forefront of
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<acronym>ORDBMS</acronym> development. In addition to
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<acronym>SQL99</acronym> conformance, substantial portions
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of <acronym>SQL92</acronym> are also supported.
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Although we strive for <acronym>SQL92</acronym> compliance,
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there are some aspects of the standard
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that are ill considered and which should not live through subsequent standards.
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<productname>Postgres</productname> will not make great efforts to
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conform to these features; however, these tend to apply in little-used
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or obsure cases, and a typical user is not likely to run into them.
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</para>
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<note>
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<title>Compatibility</title>
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<para>
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The following types (or spellings thereof) are specified by SQL:
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<type>bit</type>, <type>bit varying</type>, <type>boolean</type>,
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<type>char</type>, <type>character</type>, <type>character
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varying</type>, <type>varchar</type>, <type>date</type>,
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<type>double precision</type>, <type>integer</type>,
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<type>interval</type>, <type>numeric</type>, <type>decimal</type>,
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<type>real</type>, <type>smallint</type>, <type>time</type>,
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<type>timestamp</type> (both with or without time zone).
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</para>
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</note>
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<para>
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Most of the input and output functions corresponding to the
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@ -259,19 +252,9 @@ $Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.46 2000/12/22 18:57:49 pe
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Some of the input and output functions are not invertible. That is,
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the result of an output function may lose precision when compared to
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the original input.
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<note>
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<para>
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Floating point numbers are allowed to retain
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most of the intrinsic precision of the type (typically 15 digits for doubles,
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6 digits for 4-byte floats).
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Other types with underlying floating point fields (e.g. geometric
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types) carry similar precision.
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</para>
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</note>
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</para>
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<sect1 id="numeric-types">
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<sect1 id="datatype-numeric">
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<title>Numeric Types</title>
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<para>
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@ -293,49 +276,53 @@ $Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.46 2000/12/22 18:57:49 pe
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<entry>Range</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>smallint</entry>
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<entry>2 bytes</entry>
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<entry>Fixed-precision</entry>
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<entry>-32768 to +32767</entry>
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</row>
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<row>
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<entry>integer</entry>
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<entry>4 bytes</entry>
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<entry>Usual choice for fixed-precision</entry>
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<entry>-2147483648 to +2147483647</entry>
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</row>
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<row>
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<entry>bigint</entry>
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<entry>8 bytes</entry>
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<entry>Very large range fixed-precision</entry>
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<entry>about 18 decimal places</entry>
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</row>
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<row>
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<entry>decimal</entry>
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<entry>variable</entry>
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<entry>User-specified precision</entry>
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<entry>no limit</entry>
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</row>
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<row>
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<entry>float4</entry>
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<entry>4 bytes</entry>
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<entry>Variable-precision</entry>
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<entry>6 decimal places</entry>
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</row>
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<row>
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<entry>float8</entry>
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<entry>8 bytes</entry>
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<entry>Variable-precision</entry>
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<entry>15 decimal places</entry>
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</row>
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<row>
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<entry>int2</entry>
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<entry>2 bytes</entry>
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<entry>Fixed-precision</entry>
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<entry>-32768 to +32767</entry>
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</row>
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<row>
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<entry>int4</entry>
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<entry>4 bytes</entry>
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<entry>Usual choice for fixed-precision</entry>
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<entry>-2147483648 to +2147483647</entry>
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</row>
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<row>
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<entry>int8</entry>
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<entry>8 bytes</entry>
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<entry>Very large range fixed-precision</entry>
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<entry>~18 decimal places</entry>
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</row>
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<row>
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<entry>numeric</entry>
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<entry>variable</entry>
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<entry>User-specified precision</entry>
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<entry>no limit</entry>
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</row>
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<row>
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<entry>real</entry>
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<entry>4 bytes</entry>
|
||||
<entry>Variable-precision</entry>
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||||
<entry>6 decimal places</entry>
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</row>
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<row>
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<entry>double precision</entry>
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||||
<entry>8 bytes</entry>
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||||
<entry>Variable-precision</entry>
|
||||
<entry>15 decimal places</entry>
|
||||
</row>
|
||||
|
||||
<row>
|
||||
<entry>serial</entry>
|
||||
<entry>4 bytes</entry>
|
||||
|
|
@ -353,11 +340,11 @@ $Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.46 2000/12/22 18:57:49 pe
|
|||
</para>
|
||||
|
||||
<para>
|
||||
The <type>int8</type> type may not be available on all platforms since
|
||||
The <type>bigint</type> type may not be available on all platforms since
|
||||
it relies on compiler support for eight-byte integers.
|
||||
</para>
|
||||
|
||||
<sect2>
|
||||
<sect2 id="datatype-serial">
|
||||
<title>The Serial Type</title>
|
||||
|
||||
<para>
|
||||
|
|
@ -403,7 +390,7 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (<replaceabl
|
|||
</sect2>
|
||||
</sect1>
|
||||
|
||||
<sect1 id="monetary-types">
|
||||
<sect1 id="datatype-money">
|
||||
<title>Monetary Type</title>
|
||||
|
||||
<note>
|
||||
|
|
@ -455,15 +442,15 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (<replaceabl
|
|||
|
||||
</sect1>
|
||||
|
||||
<sect1 id="character-types">
|
||||
<sect1 id="datatype-character">
|
||||
<title>Character Types</title>
|
||||
|
||||
<para>
|
||||
<acronym>SQL92</acronym> defines two primary character types:
|
||||
<type>char</type> and <type>varchar</type>.
|
||||
<acronym>SQL</acronym> defines two primary character types:
|
||||
<type>character</type> and <type>character varying</type>.
|
||||
<productname>Postgres</productname> supports these types, in
|
||||
addition to the more general <type>text</type> type,
|
||||
which unlike <type>varchar</type>
|
||||
which unlike <type>character varying</type>
|
||||
does not require an explicit declared upper
|
||||
limit on the size of the field.
|
||||
</para>
|
||||
|
|
@ -483,16 +470,16 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (<replaceabl
|
|||
</thead>
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>"char"</entry>
|
||||
<entry>1 byte</entry>
|
||||
<entry><acronym>SQL92</acronym>-compatible</entry>
|
||||
<entry>Single character</entry>
|
||||
<entry>character(n), char(n)</entry>
|
||||
<entry>(4+n) bytes</entry>
|
||||
<entry><acronym>SQL</acronym>-compatible</entry>
|
||||
<entry>Fixed-length blank padded</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>char(n)</entry>
|
||||
<entry>character varying(n), varchar(n)</entry>
|
||||
<entry>(4+n) bytes</entry>
|
||||
<entry><acronym>SQL92</acronym>-compatible</entry>
|
||||
<entry>Fixed-length blank padded</entry>
|
||||
<entry><acronym>SQL</acronym>-compatible</entry>
|
||||
<entry>Variable-length with limit</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>text</entry>
|
||||
|
|
@ -500,26 +487,32 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (<replaceabl
|
|||
<entry>Most flexible</entry>
|
||||
<entry>Variable unlimited length</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>varchar(n)</entry>
|
||||
<entry>(4+n) bytes</entry>
|
||||
<entry><acronym>SQL92</acronym>-compatible</entry>
|
||||
<entry>Variable-length with limit</entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</table>
|
||||
|
||||
<note>
|
||||
<para>
|
||||
Although the type <type>text</type> is not SQL-compliant, many
|
||||
other RDBMS packages have it as well.
|
||||
</para>
|
||||
</note>
|
||||
</para>
|
||||
|
||||
<para>
|
||||
There is one other fixed-length character type in <productname>Postgres</productname>.
|
||||
The <type>name</type> type exists <emphasis>only</emphasis> for
|
||||
storage of internal catalog names and
|
||||
is not intended for use by the general user.
|
||||
Its length is currently defined as 32 bytes (31 characters plus terminator)
|
||||
but should be reference using NAMEDATALEN.
|
||||
The length is set at compile time (and is therefore adjustable for
|
||||
special uses); the default maximum length may change in a future release.
|
||||
There are two other fixed-length character types in
|
||||
<productname>Postgres</productname>. The <type>name</type> type
|
||||
exists <emphasis>only</emphasis> for storage of internal catalog
|
||||
names and is not intended for use by the general user. Its length
|
||||
is currently defined as 32 bytes (31 characters plus terminator)
|
||||
but should be referenced using the macro
|
||||
<symbol>NAMEDATALEN</symbol>. The length is set at compile time
|
||||
(and is therefore adjustable for special uses); the default
|
||||
maximum length may change in a future release. The type
|
||||
<type>"char"</type> (note the quotes) is different from
|
||||
<type>char(1)</type> in that it only uses one byte of storage. It
|
||||
is internally used in the system catalogs as a poor-man's
|
||||
enumeration type.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
|
|
@ -535,6 +528,11 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (<replaceabl
|
|||
</row>
|
||||
</thead>
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>"char"</entry>
|
||||
<entry>1 byte</entry>
|
||||
<entry>Single character internal type</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>name</entry>
|
||||
<entry>32 bytes</entry>
|
||||
|
|
@ -547,7 +545,7 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (<replaceabl
|
|||
|
||||
</sect1>
|
||||
|
||||
<sect1 id="datetime-types">
|
||||
<sect1 id="datatype-datetime">
|
||||
<title>Date/Time Types</title>
|
||||
|
||||
<para>
|
||||
|
|
@ -641,7 +639,7 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (<replaceabl
|
|||
</para>
|
||||
|
||||
|
||||
<sect2>
|
||||
<sect2 id="datatype-datetime-input">
|
||||
<title>Date/Time Input</title>
|
||||
|
||||
<para>
|
||||
|
|
@ -658,7 +656,7 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (<replaceabl
|
|||
</para>
|
||||
|
||||
<para>
|
||||
See <xref endterm="datetime-appendix-title" linkend="datetime-appendix-title">
|
||||
See <xref linkend="datetime-appendix">
|
||||
for the exact parsing rules of date/time input and for the recognized time zones.
|
||||
</para>
|
||||
|
||||
|
|
@ -956,7 +954,7 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (<replaceabl
|
|||
</para>
|
||||
|
||||
<para>
|
||||
Refer to <xref endterm="timezone-title" linkend="timezone"> for
|
||||
Refer to <xref linkend="datatype-timezone-table"> for
|
||||
more examples of time zones.
|
||||
</para>
|
||||
</sect3>
|
||||
|
|
@ -984,8 +982,8 @@ January 8 04:05:06 1999 PST
|
|||
</para>
|
||||
|
||||
<para>
|
||||
<table tocentry="1" id="timezone">
|
||||
<title id="timezone-title"><productname>Postgres</productname> Time Zone Input</title>
|
||||
<table tocentry="1" id="datatype-timezone-table">
|
||||
<title><productname>Postgres</productname> Time Zone Input</title>
|
||||
<titleabbrev>Time Zone Inputs</titleabbrev>
|
||||
<tgroup cols="2">
|
||||
<thead>
|
||||
|
|
@ -1112,7 +1110,7 @@ January 8 04:05:06 1999 PST
|
|||
</sect2>
|
||||
|
||||
|
||||
<sect2>
|
||||
<sect2 id="datatype-datetime-output">
|
||||
<title>Date/Time Output</title>
|
||||
|
||||
<para>
|
||||
|
|
@ -1231,7 +1229,7 @@ January 8 04:05:06 1999 PST
|
|||
|
||||
</sect2>
|
||||
|
||||
<sect2>
|
||||
<sect2 id="datatype-timezones">
|
||||
<title>Time Zones</title>
|
||||
|
||||
<para>
|
||||
|
|
@ -1351,7 +1349,7 @@ January 8 04:05:06 1999 PST
|
|||
|
||||
</sect2>
|
||||
|
||||
<sect2>
|
||||
<sect2 id="datatype-datetime-internals">
|
||||
<title>Internals</title>
|
||||
|
||||
<para>
|
||||
|
|
@ -1370,22 +1368,21 @@ January 8 04:05:06 1999 PST
|
|||
|
||||
</sect1>
|
||||
|
||||
<sect1 id="boolean-type">
|
||||
<sect1 id="datatype-boolean">
|
||||
<title>Boolean Type</title>
|
||||
|
||||
<para>
|
||||
<productname>Postgres</productname> supports <type>bool</type> as
|
||||
the <acronym>SQL99</acronym> boolean type.
|
||||
<type>bool</type> can have one of only two states: 'true' or 'false'.
|
||||
A third state, 'unknown', is not
|
||||
implemented and is not suggested in <acronym>SQL99</acronym>;
|
||||
<acronym>NULL</acronym> is an
|
||||
effective substitute. <type>bool</type> can be used in any boolean expression,
|
||||
and boolean expressions
|
||||
always evaluate to a result compatible with this type.</para>
|
||||
<productname>Postgres</productname> supports the
|
||||
<acronym>SQL99</acronym> <type>boolean</type> type.
|
||||
<type>boolean</type> can have one of only two states: 'true' or
|
||||
'false'. A third state, 'unknown', is represented by the SQL NULL
|
||||
state. <type>boolean</type> can be used in any boolean expression,
|
||||
and boolean expressions always evaluate to a result compatible
|
||||
with this type.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
<type>bool</type> uses 1 byte of storage.
|
||||
<type>boolean</type> uses 1 byte of storage.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
|
|
@ -1417,7 +1414,7 @@ January 8 04:05:06 1999 PST
|
|||
</para>
|
||||
</sect1>
|
||||
|
||||
<sect1 id="geometric-types">
|
||||
<sect1 id="datatype-geometric">
|
||||
<title>Geometric Types</title>
|
||||
|
||||
<para>
|
||||
|
|
@ -1746,7 +1743,7 @@ January 8 04:05:06 1999 PST
|
|||
|
||||
</sect1>
|
||||
|
||||
<sect1 id="net-types">
|
||||
<sect1 id="datatype-net-types">
|
||||
<title>Network Address Data Types</title>
|
||||
|
||||
<para>
|
||||
|
|
@ -1755,7 +1752,7 @@ January 8 04:05:06 1999 PST
|
|||
types, because these types offer input error checking and several
|
||||
specialized operators and functions.
|
||||
|
||||
<table tocentry="1" id="net-types-table">
|
||||
<table tocentry="1" id="datatype-net-types-table">
|
||||
<title>Network Address Data Types</title>
|
||||
<tgroup cols="4">
|
||||
<thead>
|
||||
|
|
@ -1799,7 +1796,7 @@ January 8 04:05:06 1999 PST
|
|||
</para>
|
||||
|
||||
|
||||
<sect2 id="inet-type">
|
||||
<sect2 id="datatype-inet">
|
||||
<title><type>inet</type></title>
|
||||
|
||||
<para>
|
||||
|
|
@ -1825,7 +1822,7 @@ January 8 04:05:06 1999 PST
|
|||
</para>
|
||||
</sect2>
|
||||
|
||||
<sect2 id="cidr-type">
|
||||
<sect2 id="datatype-cidr">
|
||||
<title><type>cidr</></title>
|
||||
|
||||
<para>
|
||||
|
|
@ -1918,7 +1915,7 @@ January 8 04:05:06 1999 PST
|
|||
</para>
|
||||
</sect2>
|
||||
|
||||
<sect2 id="inet-vs-cidr">
|
||||
<sect2 id="datatype-inet-vs-cidr">
|
||||
<title><type>inet</type> vs <type>cidr</type></title>
|
||||
|
||||
<para>
|
||||
|
|
@ -1936,7 +1933,7 @@ January 8 04:05:06 1999 PST
|
|||
</para>
|
||||
</sect2>
|
||||
|
||||
<sect2 id="macaddr-type">
|
||||
<sect2 id="datatype-macaddr">
|
||||
<title><type>macaddr</></>
|
||||
|
||||
<para>
|
||||
|
|
@ -1955,6 +1952,40 @@ January 8 04:05:06 1999 PST
|
|||
|
||||
</sect1>
|
||||
|
||||
<sect1 id="datatype-bit">
|
||||
<title>Bit String Types</title>
|
||||
|
||||
<para>
|
||||
Bit strings are strings of 1's and 0's. They can be used to store
|
||||
or visualize bit masks. There are two SQL bit types:
|
||||
<type>BIT(<replaceable>x</replaceable>)</type> and <type>BIT
|
||||
VARYING(<replaceable>x</replaceable>)</type>; the
|
||||
<replaceable>x</replaceable> specifies the maximum length.
|
||||
<type>BIT</type> type data is automatically padded with 0's on the
|
||||
right to the maximum length, <type>BIT VARYING</type> is of
|
||||
variable length. <type>BIT</type> without length is requivalent
|
||||
to <literal>BIT(1)</literal>, <type>BIT VARYING</type> means
|
||||
unlimited length. Input data that is longer than the allowed
|
||||
length will be truncated. Refer to <xref
|
||||
linkend="sql-syntax-bit-strings"> for information about the syntax
|
||||
of bit string constants. Bit-logical operators and string
|
||||
manipulation functions are available; see <xref
|
||||
linkend="functions">.
|
||||
</para>
|
||||
|
||||
<informalexample>
|
||||
<para>
|
||||
Some examples:
|
||||
<programlisting>
|
||||
CREATE TABLE test (a BIT(3), b BIT VARYING(5));
|
||||
INSERT INTO test VALUES (B'101', B'00');
|
||||
SELECT SUBSTRING(b FROM 1 FOR 2) FROM test;
|
||||
</programlisting>
|
||||
</para>
|
||||
</informalexample>
|
||||
|
||||
</sect1>
|
||||
|
||||
</chapter>
|
||||
|
||||
<!-- Keep this comment at the end of the file
|
||||
|
|
|
|||
|
|
@ -1,4 +1,4 @@
|
|||
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.46 2000/12/22 18:00:24 tgl Exp $ -->
|
||||
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.47 2001/01/13 18:34:51 petere Exp $ -->
|
||||
|
||||
<chapter id="functions">
|
||||
<title>Functions and Operators</title>
|
||||
|
|
@ -184,42 +184,102 @@
|
|||
<entry>@ -5.0</entry>
|
||||
<entry>5.0</entry>
|
||||
</row>
|
||||
|
||||
<row>
|
||||
<entry> <literal>&</literal> </entry>
|
||||
<entry>Binary AND</entry>
|
||||
<entry>91 & 15</entry>
|
||||
<entry>11</entry>
|
||||
</row>
|
||||
|
||||
<row>
|
||||
<entry> <literal>|</literal> </entry>
|
||||
<entry>Binary OR</entry>
|
||||
<entry>32 | 3</entry>
|
||||
<entry>35</entry>
|
||||
</row>
|
||||
|
||||
<row>
|
||||
<entry> <literal>#</literal> </entry>
|
||||
<entry>Binary XOR</entry>
|
||||
<entry>17 # 5</entry>
|
||||
<entry>20</entry>
|
||||
</row>
|
||||
|
||||
<row>
|
||||
<entry> <literal>~</literal> </entry>
|
||||
<entry>Binary NOT</entry>
|
||||
<entry>~1</entry>
|
||||
<entry>-2</entry>
|
||||
</row>
|
||||
|
||||
<row>
|
||||
<entry> << </entry>
|
||||
<entry>Binary shift left</entry>
|
||||
<entry>1 << 4</entry>
|
||||
<entry>16</entry>
|
||||
</row>
|
||||
|
||||
<row>
|
||||
<entry> >> </entry>
|
||||
<entry>Binary shift right</entry>
|
||||
<entry>8 >> 2</entry>
|
||||
<entry>2</entry>
|
||||
</row>
|
||||
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</table>
|
||||
|
||||
<!--
|
||||
<ROW>
|
||||
<ENTRY> & </ENTRY>
|
||||
<ENTRY>Binary AND</ENTRY>
|
||||
<ENTRY>91 & 15</ENTRY>
|
||||
</ROW>
|
||||
<ROW>
|
||||
<ENTRY> | </ENTRY>
|
||||
<ENTRY>Binary OR</ENTRY>
|
||||
<ENTRY>32 | 3</ENTRY>
|
||||
</ROW>
|
||||
<ROW>
|
||||
<ENTRY> # </ENTRY>
|
||||
<ENTRY>Binary XOR</ENTRY>
|
||||
<ENTRY>15 # 4</ENTRY>
|
||||
</ROW>
|
||||
<ROW>
|
||||
<ENTRY> ~ </ENTRY>
|
||||
<ENTRY>Binary NOT</ENTRY>
|
||||
<ENTRY>~1</ENTRY>
|
||||
</ROW>
|
||||
<ROW>
|
||||
<ENTRY> << </ENTRY>
|
||||
<ENTRY>Binary shift left</ENTRY>
|
||||
<ENTRY>1 << 4</ENTRY>
|
||||
</ROW>
|
||||
<ROW>
|
||||
<ENTRY> >> </ENTRY>
|
||||
<ENTRY>Binary shift right</ENTRY>
|
||||
<ENTRY>8 >> 2</ENTRY>
|
||||
</ROW>
|
||||
-->
|
||||
<para>
|
||||
The <quote>binary</quote> operators are also available for the bit
|
||||
string types <type>BIT</type> and <type>BIT VARYING</type>.
|
||||
|
||||
<table>
|
||||
<title>Bit String Binary Operators</title>
|
||||
|
||||
<tgroup cols="2">
|
||||
<thead>
|
||||
<row>
|
||||
<entry>Example</entry>
|
||||
<entry>Result</entry>
|
||||
</row>
|
||||
</thead>
|
||||
|
||||
<tbody>
|
||||
<row>
|
||||
<entry>B'10001' & B'01101'</entry>
|
||||
<entry>00001</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>B'10001' | B'01101'</entry>
|
||||
<entry>11101</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>B'10001' # B'01101'</entry>
|
||||
<entry>11110</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>~ B'10001'</entry>
|
||||
<entry>01110</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>B'10001' << 3</entry>
|
||||
<entry>01000</entry>
|
||||
</row>
|
||||
<row>
|
||||
<entry>B'10001' >> 2</entry>
|
||||
<entry>00100</entry>
|
||||
</row>
|
||||
</tbody>
|
||||
</tgroup>
|
||||
</table>
|
||||
|
||||
Bit string arguments to <literal>&</literal>, <literal>|</literal>,
|
||||
and <literal>#</literal> must be of equal length. When bit
|
||||
shifting, the original length of the string is preserved, as shown
|
||||
here.
|
||||
</para>
|
||||
|
||||
<table tocentry="1">
|
||||
<title>Mathematical Functions</title>
|
||||
|
|
@ -484,7 +544,8 @@
|
|||
wary of potential effects of the automatic padding when using the
|
||||
<type>CHARACTER</type> type. Generally the functions described
|
||||
here also work on data of non-string types by converting that data
|
||||
to a string representation first.
|
||||
to a string representation first. Some functions also exist
|
||||
natively for bit string types.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
|
|
|
|||
|
|
@ -1,5 +1,5 @@
|
|||
<!--
|
||||
$Header: /cvsroot/pgsql/doc/src/sgml/syntax.sgml,v 1.33 2001/01/08 22:07:47 tgl Exp $
|
||||
$Header: /cvsroot/pgsql/doc/src/sgml/syntax.sgml,v 1.34 2001/01/13 18:34:51 petere Exp $
|
||||
-->
|
||||
|
||||
<chapter id="sql-syntax">
|
||||
|
|
@ -232,7 +232,7 @@ SELECT 'foo' 'bar';
|
|||
</para>
|
||||
</sect3>
|
||||
|
||||
<sect3>
|
||||
<sect3 id="sql-syntax-bit-strings">
|
||||
<title>Bit String Constants</title>
|
||||
|
||||
<para>
|
||||
|
|
|
|||
Loading…
Reference in New Issue