Fix HTML markup and add NULL sorting item to existing NULL FAQ item.
Greg Sabino Mullan
This commit is contained in:
Bruce Momjian
parent
d2557833e9
commit
026a8510a3
39
doc/FAQ
39
doc/FAQ
@ -1,7 +1,7 @@
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Frequently Asked Questions (FAQ) for PostgreSQL
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Last updated: Mon Feb 14 23:35:09 EST 2005
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Last updated: Thu Feb 24 19:32:04 EST 2005
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Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
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@ -59,7 +59,8 @@
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4.8) How do I perform regular expression searches and case-insensitive
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regular expression searches? How do I use an index for
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case-insensitive searches?
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4.9) In a query, how do I detect if a field is NULL?
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4.9) In a query, how do I detect if a field is NULL? How can I sort on
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whether a field is NULL or not?
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4.10) What is the difference between the various character types?
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4.11.1) How do I create a serial/auto-incrementing field?
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4.11.2) How do I get the value of a SERIAL insert?
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@ -119,7 +120,8 @@
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PostgreSQL Data Base Management System
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Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
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Portions Copyright (c) 1994-6 Regents of the University of California
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Portions Copyright (c) 1994-1996 Regents of the University of
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California
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Permission to use, copy, modify, and distribute this software and its
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documentation for any purpose, without fee, and without a written
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@ -160,7 +162,8 @@
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1.4) Where can I get PostgreSQL?
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The primary anonymous ftp site for PostgreSQL is
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ftp://ftp.PostgreSQL.org/pub. For mirror sites, see our main web site.
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ftp://ftp.PostgreSQL.org/pub/. For mirror sites, see our main web
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site.
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1.5) Where can I get support?
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@ -177,14 +180,14 @@
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EFNet.
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A list of commercial support companies is available at
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http://techdocs.postg resql.org/companies.php.
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http://techdocs.postgresql.org/companies.php.
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1.6) How do I submit a bug report?
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Visit the PostgreSQL bug form at
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http://www.postgresql.org/support/submitbug.
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Also check out our ftp site ftp://ftp.PostgreSQL.org/pub to see if
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Also check out our ftp site ftp://ftp.PostgreSQL.org/pub/ to see if
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there is a more recent PostgreSQL version.
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1.7) What is the latest release?
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@ -318,15 +321,15 @@
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For Web integration, PHP (http://www.php.net) is an excellent
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interface.
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For complex cases, many use the Perl and CGI.pm or mod_perl.
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For complex cases, many use the Perl DBD::Pg with CGI.pm or mod_perl.
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2.3) Does PostgreSQL have a graphical user interface?
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Yes, there are several graphical interfaces to PostgreSQL available.
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These include pgAdmin III (http://www.pgadmin.org, PgAccess
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http://www.pgaccess.org), RHDB Admin (http://sources.redhat.com/rhd b/
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), TORA (http://www.globecom.net/tora/, partly commercial), and Rekall
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( http://www.rekallrevealed.org/). There is also PhpPgAdmin (
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http://www.pgaccess.org), RHDB Admin (http://sources.redhat.com/rhdb/
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), TORA ( http://www.globecom.net/tora/, partly commercial), and
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Rekall ( http://www.rekallrevealed.org/). There is also PhpPgAdmin (
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http://phppgadmin.sourceforge.net/ ), a web-based interface to
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PostgreSQL.
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@ -634,10 +637,22 @@
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expresssion index, it will be used:
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CREATE INDEX tabindex ON tab (lower(col));
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4.9) In a query, how do I detect if a field is NULL?
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4.9) In a query, how do I detect if a field is NULL? How can I sort on
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whether a field is NULL or not?
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You test the column with IS NULL and IS NOT NULL.
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SELECT *
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FROM tab
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WHERE col IS NULL;
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To sort by the NULLIS NULL
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and IS NOT NULL modifiers in your WHERE clause. Things that are true
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will sort higher than things that are false, so the following will put
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NULL entries at the top of the resulting list:
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SELECT *
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FROM tab
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ORDER BY (col IS NOT NULL)
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4.10) What is the difference between the various character types?
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Type Internal Name Notes
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@ -10,7 +10,7 @@
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alink="#0000ff">
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<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
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<P>Last updated: Mon Feb 14 23:35:09 EST 2005</P>
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<P>Last updated: Thu Feb 24 19:32:04 EST 2005</P>
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<P>Current maintainer: Bruce Momjian (<A href=
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"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)
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@ -85,7 +85,8 @@
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searches and case-insensitive regular expression searches? How do I
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use an index for case-insensitive searches?<BR>
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<A href="#4.9">4.9</A>) In a query, how do I detect if a field
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is <SMALL>NULL</SMALL>?<BR>
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is <SMALL>NULL</SMALL>? How can I sort on whether a field is <SMALL>
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NULL</SMALL> or not?<BR>
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<A href="#4.10">4.10</A>) What is the difference between the
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various character types?<BR>
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<A href="#4.11.1">4.11.1</A>) How do I create a
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@ -162,7 +163,7 @@
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<P>PostgreSQL Data Base Management System</P>
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<P>Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
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Portions Copyright (c) 1994-6 Regents of the University of California</P>
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Portions Copyright (c) 1994-1996 Regents of the University of California</P>
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<P>Permission to use, copy, modify, and distribute this software
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and its documentation for any purpose, without fee, and without a
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@ -206,7 +207,7 @@
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<H4><A name="1.4">1.4</A>) Where can I get PostgreSQL?</H4>
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<P>The primary anonymous ftp site for PostgreSQL is <A href=
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"ftp://ftp.PostgreSQL.org/pub">ftp://ftp.PostgreSQL.org/pub</A>.
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"ftp://ftp.PostgreSQL.org/pub/">ftp://ftp.PostgreSQL.org/pub/</A>.
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For mirror sites, see our main web site.</P>
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<H4><A name="1.5">1.5</A>) Where can I get support?</H4>
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@ -225,8 +226,8 @@
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(<I>#postgresqlfr</I>). There is also a PostgreSQL channel on EFNet.
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<P>A list of commercial support companies is available at <A href=
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"http://techdocs.postgresql.org/companies.php">http://techdocs.postg
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resql.org/companies.php</A>.</P>
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"http://techdocs.postgresql.org/companies.php">
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http://techdocs.postgresql.org/companies.php</A>.</P>
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<H4><A name="1.6">1.6</A>) How do I submit a bug report?</H4>
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@ -235,7 +236,7 @@
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http://www.postgresql.org/support/submitbug</A>.</P>
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<P>Also check out our ftp site <A href=
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"ftp://ftp.PostgreSQL.org/pub">ftp://ftp.PostgreSQL.org/pub</A> to
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"ftp://ftp.PostgreSQL.org/pub/">ftp://ftp.PostgreSQL.org/pub/</A> to
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see if there is a more recent PostgreSQL version.</P>
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<H4><A name="1.7">1.7</A>) What is the latest release?</H4>
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@ -411,7 +412,8 @@
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href="http://www.php.net">http://www.php.net</A>) is an excellent
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interface.</P>
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<P>For complex cases, many use the Perl and CGI.pm or mod_perl.</P>
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<P>For complex cases, many use the Perl DBD::Pg with CGI.pm or
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mod_perl.</P>
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<H4><A name="2.3">2.3</A>) Does PostgreSQL have a graphical user
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interface?</H4>
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@ -421,10 +423,9 @@
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href="http://www.pgadmin.org">http://www.pgadmin.org</a>, PgAccess
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<a href="http://www.pgaccess.org"> http://www.pgaccess.org</a>),
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RHDB Admin (<a
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href="http://sources.redhat.com/rhdb/">http://sources.redhat.com/rhd
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b/ </a>), TORA (<a
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href="http://www.globecom.net/tora/">http://www.globecom.net/tora/</a>,
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partly commercial), and Rekall (<a
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href="http://sources.redhat.com/rhdb/">http://sources.redhat.com/rhdb/
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</a>), TORA (<a href="http://www.globecom.net/tora/">
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http://www.globecom.net/tora/</a>, partly commercial), and Rekall (<a
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href="http://www.rekallrevealed.org/">
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http://www.rekallrevealed.org/</a>). There is also PhpPgAdmin (<a
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href="http://phppgadmin.sourceforge.net/">
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@ -815,11 +816,29 @@ table?</TD><TD>unlimited</TD></TR>
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</PRE>
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<H4><A name="4.9">4.9</A>) In a query, how do I detect if a field
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is <SMALL>NULL</SMALL>?</H4>
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is <SMALL>NULL</SMALL>? How can I sort on whether a field is <SMALL>
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NULL</SMALL> or not?</H4>
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<P>You test the column with <SMALL>IS NULL</SMALL> and <SMALL>IS
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NOT NULL</SMALL>.</P>
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<PRE>
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SELECT *
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FROM tab
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WHERE col IS NULL;
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</PRE>
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<P>To sort by the <SMALL>NULL</SMALL status, use the <SMALL>IS NULL</SMALL>
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and <SMALL>IS NOT NULL</SMALL> modifiers in your <SMALL>WHERE</SMALL> clause.
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Things that are <I>true</I> will sort higher than things that are <I>false</I>,
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so the following will put NULL entries at the top of the resulting list:</P>
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<PRE>
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SELECT *
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FROM tab
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ORDER BY (col IS NOT NULL)
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</PRE>
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<H4><A name="4.10">4.10</A>) What is the difference between the
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various character types?</H4>
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<BLOCKQUOTE>
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