database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-28 23:42:10 +03:00
Code Activity

Remove outer join simulation using UNION now that we have had outer

Browse Source 
joins for quite a long time.
This commit is contained in:
Bruce Momjian
2005-02-01 02:35:48 +00:00
parent 2de7ebe910
commit 3c16965995
2 changed files with 4 additions and 33 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
doc/src/FAQ/FAQ.html
View File

@ -10,7 +10,7 @@
alink="#0000ff">
<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
<P>Last updated: Mon Jan 31 21:31:39 EST 2005</P>
<P>Last updated: Mon Jan 31 21:35:15 EST 2005</P>
<P>Current maintainer: Bruce Momjian (<A href=
"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)
@ -1006,7 +1006,7 @@ length</TD></TR>
<P>Use <I>CURRENT_TIMESTAMP</I>:</P>
<PRE>
CREATE TABLE test (x int, modtime timestamp DEFAULT CURRENT_TIMESTAMP );
CREATE TABLE test (x int, modtime TIMESTAMP DEFAULT CURRENT_TIMESTAMP );
</PRE>
<H4><A name="4.17">4.17</A>) How do I perform an outer join?</H4>
@ -1032,23 +1032,6 @@ length</TD></TR>
<SMALL>RIGHT</SMALL>, and <SMALL>FULL</SMALL> joins. Ordinary joins
are called <SMALL>INNER</SMALL> joins.</P>
<P>In previous releases, outer joins can be simulated using
<SMALL>UNION</SMALL> and <SMALL>NOT IN</SMALL>. For example, when
joining <I>tab1</I> and <I>tab2</I>, the following query does an
<I>outer</I> join of the two tables:<BR>
<BR>
</P>
<PRE>
SELECT tab1.col1, tab2.col2
FROM tab1, tab2
WHERE tab1.col1 = tab2.col1
UNION ALL
SELECT tab1.col1, NULL
FROM tab1
WHERE tab1.col1 NOT IN (SELECT tab2.col1 FROM tab2)
ORDER BY col1
</PRE>
<H4><A name="4.18">4.18</A>) How do I perform queries using
multiple databases?</H4>