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Cartesian-Join with the blank table

Posted on 2008-06-25
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Last Modified: 2012-06-27
Sample Query:                                                                                    
                                                                                                 
SELECT     *                                                                                      
FROM       TEMP01,TEMP02,TEMP03,TEMP04,TEMP05,TEMP06,TEMP07,TEMP08,TEMP09,TEMP10,                
           TEMP11,TEMP12,TEMP13,TEMP14,TEMP15,TEMP16,TEMP17,TEMP18,TEMP19,                        
           TEMP20,TEMP21,TEMP22                                                                  
                                                                                                 
I have to DO the Cartesian-Join with all the 22 Tables, The problem is if any one of the table is
blank then the result set also empty,                                                            
                                                                                                 
How can i handle this?. In the table set any table/Combination can be blank.                      
                                                                                                 
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Question by:midwestexp
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6 Comments
 
LVL 74

Expert Comment

by:sdstuber
ID: 21869987
you would have to do an outer join to any table that might be missing data.

however,  are you sure you really need to do a 22-way join?
0
 

Author Comment

by:midwestexp
ID: 21870935
Yes i have to include all the 22 Tables, Please explain me How to Do that.
0
 
LVL 10

Expert Comment

by:dbmullen
ID: 21871412
is this a trick question?  I'm trying to think of a reason to ever do this.
do all of the tables have the same number of columns?
what is the ddl for temp01?

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Author Comment

by:midwestexp
ID: 21871705
Each table have only one column,

create table temp01 (
    a varchar2(1)
)
0
 
LVL 27

Accepted Solution

by:
sujith80 earned 500 total points
ID: 21872064
Cartesian join of 22 tables will be a bad idea, if they are big tables. Probably you can do something programmatically to achieve the actual goal behid this.
To answer the question you may use a query like this, extend it for the 22 tables.
select * from 
(select * from TEMP01 union all select null from dual where not exists(select 1 from TEMP01 )) , 
(select * from TEMP02 union all select null from dual where not exists(select 1 from TEMP02 )) , 
(select * from TEMP03 union all select null from dual where not exists(select 1 from TEMP03 )) 

Open in new window

0
 

Author Closing Comment

by:midwestexp
ID: 31470774
Thank You Very Much.
0

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