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How the join works

782493May 18 2011 — edited May 19 2011
Hi,

Could you please tell me how the below join works

Select a.col1,a,col2,b.col1,c.col1,d.col1
from Table1 a, Table2 b, Table3 c, Table4 d
where
a.col4 = b.col4 (+)
and c.col4(+) = d.col4

How do this tables are joining and displays the result.
This post has been answered by Frank Kulash on May 18 2011
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Comments

sb92075
How do this tables are joining and displays the result.
nice example of Cartesian Product!
782493
Thx

Will the below item work ?

Select a.col1,a,col2,b.col1,c.col1,d.col1
from Table1 a, Table2 b, Table3 c, Table4 d
where
a.col4 = b.col4
b.Col3=c.col3
and c.col4(+) = d.col4
Frank Kulash
Answer
Hi,
VJ wrote:
Hi,

Could you please tell me how the below join works

Select a.col1,a,col2,b.col1,c.col1,d.col1
from Table1 a, Table2 b, Table3 c, Table4 d
where
a.col4 = b.col4 (+)
and c.col4(+) = d.col4
(1) There is an inner join between a and b: rows in a will be joined to rows in b if they have the same value of col4.
(2) There is an outer join between c and d: rows in c will be joined to rows in d if they have the same value of col4, but rows from c will appear regardless of whether they match or not.
(3) There are no other join conditions, so there is a cross join between the result sets of (1) and (2): every row in each will be joined to every row in the other.
Marked as Answer by 782493 · Sep 27 2020
860993
This is my thinking method.

first step is cross join and inner join but excludeing left join.
second step is left join.
Select a.col1,a,col2,b.col1,c.col1,d.col1
from Table1 a
inner join Table2 b on a.col4 = b.col4
cross join Table3 c
left join Table4 d on c.col4 = d.col4
782493
Thx
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Locked on Jun 16 2011
Added on May 18 2011
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