Joins

[Former Member]

Hi Experts,

In Universe level How many joins we can create?what are the types.

Could any one help me..

Edited by: ramesh.sap on Feb 1, 2011 5:46 PM

[Former Member · Accepted solution]

Universe level we create 5 types of joins

They are:

1)inner join
2)outer join
      a)left outer join
      b)Right outer join
      c)full outer join
3)Theta join(non-equi join)
4)self-restricting join 
5)short cut join

All the best..

Praveen

Edited by: Praveen Vodela on Feb 2, 2011 3:39 PM

[former_member567937]

1) Equi Joins -

Link tables based on the equality between the

values in the column of one table and the values

in the column of another. Because the same column

is present in both tables, the join synchronizes

the two tables.

You can also create complex equi-joins, where

one join links multiple columns between two tables

2) Theta Joins -

Link tables based on a relationship other than

quality between two columns.

3) Outer Joins

Link two tables, one of which has rows that do

not match those in the common column of the

other table

4) Shortcut Joins

Join providing an alternative path between two

tables, bypassing intermediate tables, leading to

the same result, regardless of direction. Optimizes

query time by cutting long join paths as short as

possible

5) Self restricting joins

Single table join used to set a restriction on the

joins table.

[Former Member]

This message was moderated.

[Former Member]

Hai,

At universe level we have 5 types of joins

1)inner join

2)outer join

3)theta join(non-equi join)

4)self-restricting join

5)short cut join

if u create any between type join ur universe wil automatically establish complex join

[Former Member]

You can create as many joins as you need.

All join types are supported - inner, outer, complex, self-restricting and so on.

An extra join type of shortcut join can also be used; these joins will tell the query to use a shorter join path if possible but are not evaluated until after the context has been determined.

Anything that is out of the ordinary needs to be created as an inner first then you can edit the code.

It is important to set the join cardinality if you are going to be detecting contexts because the detect context algorithm uses this information.

Regards,

Mark