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In what scenario should I using cross outer join?

Posted on 2014-01-23
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When can I user cross outer join in SQL Server?
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Question by:RajG1978
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by:Koen Van Wielink
Koen Van Wielink earned 1000 total points
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A cross join produces the cartesian product of the tables you combine (all rows from table 1 x all rows from table 2). One application I can think of is if you're trying to analyze certain scenarios, and you need to have a list of all possible combinations that make up a scenario.
For example, say that you have a list of motherboard parts in 1 table, and a list of CPU parts in another table, and you want to generate a list of all the possible combinations of motherboards and CPU's (e.g. for a price list) you can use a cross join on both tables to do this.
If you use a cross join but put a link between the 2 tables in the WHERE clause it will behave like a normal inner join.
More info here:
http://technet.microsoft.com/en-us/library/ms190690(v=sql.105).aspx
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magarity earned 1000 total points
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When you have a requirement that needs that functionality; not sure how anyone here could answer that for you. Typically for a matrix of every combination: suppose you want a matrix of every color for every dress for every size:
select color, size, dress from color_table, size_table, dress_table
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