Importance Of Join

[Former Member]

Hi Techies,

I am unable to get the necessity of a join in my designer can some one please help me on this,

I have a scenario like this ,....

I have a main table A which holds all the result objects need to be shown in report,

and I have another 2 derived tables with the common columns of table A, there is a join existing in these three tables(with out the formation of loop and trap..)

Here , my question is like why we need to join table A and derived tables, though the result objects are presented from table A.......only.....

Please help me in clearing my confusion,

Thanks in Advance.

[Former Member]

Hi

If you are not using objects from other 2 derived tabels then what was the scenario that made you to create those tables?

[Former Member]

You join tables that are related to avoid cartesian products.

It almost sounds like you are engineering a universe back from a report spec, which isn't a good idea. Your universe should e there to deliver the capability to build reports, ad hoc analysis and any other information that users want from it, such as supporting Xcelsius dashboards

If you don't join two tables that belong together and allow cartesian products (or warn but let a user click through the warning) then they will end up with completely inaccurate data.

Same applies in XI3.1 or any version of Business Objects.

[former_member4998]

Hi

If you are reporting requirements meets accessing data only one table (table A) no need to include other tables unnecessary in the data foundation. That to in your scenario derived tables. So if you remove unnecessary tables and joins it will improve the performance.

why we need to join table A and derived tables, though the result objects are presented from table A ?

• So no need to join the table A with other derived tables,

• Before removing joins and deleting tables you need to find any specific reason to create derived tables (combines two or more tables (called merging tables))inserted into the Data foundation.

• Also need to check any objects defined using the other derived tables in the business layer. If you confirm there is no object definition used other derived tables you may delete joins and tables from the data foundation.

• And also use showing local dependencies in the data foundation, this command find the will find the business layers and their objects that depend on the table or column.

• So Select the other two derived tables and Right-click the table header or column name in the data foundation view and select Show Local Dependencies. it will show any objects that depend on the table or column in the business layer.

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[Former Member]

Thanks for the Info but I am working on BO 3.1 ......

[former_member4998]

Hi

Select the Table and right click form the context menu select the show associated objects.

Cartesian product occurs when you select object from different tables and there is no link defined between the tables, always give incorrect results. Best practices should not be any free standing tables in the data foundation.

Find the below link for more info.

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