mirrors/postgres
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Update FAQ.

Browse Source
This commit is contained in:
Bruce Momjian 2001-01-22 16:35:35 +00:00
parent 7e0919136a
commit 0fada37f5d
2 changed files with 14 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
doc/FAQ
View File

@ -948,7 +948,8 @@ SELECT *
4.24) How do I do an outer join? 4.24) How do I do an outer join?
PostgreSQL 7.1 and later supports outer joins. Here are two examples: PostgreSQL 7.1 and later supports outer joins using the SQL standard
syntax. Here are two examples:
SELECT * SELECT *
FROM t1 LEFT OUTER JOIN t2 ON (t1.col = t2.col); FROM t1 LEFT OUTER JOIN t2 ON (t1.col = t2.col);
@ -956,11 +957,12 @@ SELECT *
SELECT * SELECT *
FROM t1 LEFT OUTER JOIN t2 USING (col); FROM t1 LEFT OUTER JOIN t2 USING (col);
These identical queries join t1.col to t2.col, and return any unjoined These identical queries join t1.col to t2.col, and also return any
rows in t1. A RIGHT join would return unjoined rows of table t2. A unjoined rows in t1 (those with no match in t2). A RIGHT join would
FULL join would return unjoined rows from t1 and t2. The word OUTER is add unjoined rows of t2. A FULL join would return the matched rows
optional and is assumed in LEFT, RIGHT, and FULL joins. Ordinary joins plus all unjoined rows from t1 and t2. The word OUTER is optional and
are called INNER joins. is assumed in LEFT, RIGHT, and FULL joins. Ordinary joins are called
INNER joins.
In previous releases, outer joins can be simulated using UNION and NOT In previous releases, outer joins can be simulated using UNION and NOT
IN. For example, when joining tab1 and tab2, the following query does IN. For example, when joining tab1 and tab2, the following query does

11
doc/src/FAQ/FAQ.html
View File

@ -1224,8 +1224,8 @@ Lobby your company to join W3C, see http://www.w3.org/Consortium
<H4><A name="4.24">4.24</A>) How do I do an <I>outer</I> join?<BR> <H4><A name="4.24">4.24</A>) How do I do an <I>outer</I> join?<BR>
</H4> </H4>
<P>PostgreSQL 7.1 and later supports outer joins. Here are two <P>PostgreSQL 7.1 and later supports outer joins using the SQL
examples:</P> standard syntax. Here are two examples:</P>
<PRE> <PRE>
SELECT * SELECT *
FROM t1 LEFT OUTER JOIN t2 ON (t1.col = t2.col); FROM t1 LEFT OUTER JOIN t2 ON (t1.col = t2.col);
@ -1235,9 +1235,10 @@ or
SELECT * SELECT *
FROM t1 LEFT OUTER JOIN t2 USING (col); FROM t1 LEFT OUTER JOIN t2 USING (col);
</PRE> </PRE>
These identical queries join t1.col to t2.col, and return any These identical queries join t1.col to t2.col, and also return any
unjoined rows in t1. A <SMALL>RIGHT</SMALL> join would return unjoined rows in t1 (those with no match in t2). A
unjoined rows of table t2. A <SMALL>FULL</SMALL> join would return <SMALL>RIGHT</SMALL> join would add unjoined rows of t2. A
<SMALL>FULL</SMALL> join would return the matched rows plus all
unjoined rows from t1 and t2. The word <SMALL>OUTER</SMALL> is unjoined rows from t1 and t2. The word <SMALL>OUTER</SMALL> is
optional and is assumed in <SMALL>LEFT</SMALL>, optional and is assumed in <SMALL>LEFT</SMALL>,
<SMALL>RIGHT</SMALL>, and <SMALL>FULL</SMALL> joins. Ordinary joins <SMALL>RIGHT</SMALL>, and <SMALL>FULL</SMALL> joins. Ordinary joins