t*********i
发帖数: 217 | 1 Any one knows what this means?
select tbl1.xx, tbl2.xx from tbl1, tbl2 where tbl1.col1=tbl2.col2 (+)
many thanks! |
v*****r
发帖数: 1119 | 2 Oracle's traditional non-ANSI standard left outer join query, your query is
equivalent to the following two queries if using ANSI stardard:
1. select tbl1.xx, tbl2.xx
from tbl1 LEFT OUTER JOIN tbl2
on tbl1.col1=tbl2.col2;
or
2. select tbl1.xx, tbl2.xx
from tbl2 RIGHT OUTER JOIN tbl1
on tbl2.col2=tbl1.col1; |
t*********i
发帖数: 217 | 3 I see. Thanks a lot.
The syntax is a little strange. tbl1 get all records when tbl2 has a (+)
there. |
v*****r
发帖数: 1119 | 4 哈哈，如果你习惯了 +=， =+ syntax, 看 ANSI out join syntax 还觉得别扭哪。 |
s*******6
发帖数: 3 | 5 (+) is the best expression. ANSI out join is for some who is not a DB
developer. |
a9
发帖数: 21638 | 6 这个等于full outer join吗？
is
【在 v*****r 的大作中提到】
: Oracle's traditional non-ANSI standard left outer join query, your query is
: equivalent to the following two queries if using ANSI stardard:
: 1. select tbl1.xx, tbl2.xx
: from tbl1 LEFT OUTER JOIN tbl2
: on tbl1.col1=tbl2.col2;
: or
: 2. select tbl1.xx, tbl2.xx
: from tbl2 RIGHT OUTER JOIN tbl1
: on tbl2.col2=tbl1.col1;
|
f*******h
发帖数: 53 | |
v*****r
发帖数: 1119 | 8 To do "full outer join" using old oracle outer join syntax, you will need a
UNION to union left and right outer join.
Oracle old +=, =+ syntax in most cases are more concise than ANSI syntax,
but ANSI full outer join syntax seems more concise than += UNION =+ old
syntax.
【在 a9 的大作中提到】
: 这个等于full outer join吗？
:
: is
|
