Chapter 10: Advanced Objects

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In the previous chapters, you created some basic objects. In this chapter, you will add a significant amount of intelligence to columns of information. BusinessObjects provides two main categories of functionality to do this: internal BusinessObjects functions and SQL functions that are RDBMS specific. The first part of the chapter covers functionality that is specific to BusinessObjects but database independent. The second part of the chapter covers SQL commands that may be dependent on which RDBMS you use.

Reducing Maintenance with Base Objects and @Select

The @Select function is an internal BusinessObjects function that allows you, as the designer, to reuse universe objects without forcing you to repeat the entire SQL syntax. For example, take an initial object Sales that provides information on revenue in U.S. dollars. You can add a number of forms of intelligence to this object: Sales in Local Currency, Sales in Euros, Sales Adjusted for Inflation, Sales with 10% Projected Increase, and so on. These additional objects are not columns in the database; they are objects you create by using SQL commands described in the second part of this book. However, they all use the same initial column in the RDBMS. When building advanced objects with Designer, you can either select the RDBMS column or a universe object. Whenever possible, select an object. You will save time on maintenance. Imagine six months from now, the Sales column in the RDBMS is renamed. If all of the related Sales objects used the RDBMS column, that is how many objects you now must modify manually. However, if all the objects used @Select, you need to modify only the base object.

The syntax of @Select is @Select(Class\Object), where Class is the name of the class that contains the base object-for example, Measures, and Object is the name of the object that contains the base object-for example, Sales. When using @Select, you can still see the full SQL statement by clicking Show Object SQL in the SQL Editor. In all the examples in this chapter, I use @Select whenever possible but display the full SQL syntax.

Tip 

Whenever possible, use objects rather than individual RDBMS columns. This will save you work if ever you rename an RDBMS column, as you will need to modify only the SQL of the base object; Designer will automatically update the SQL for all other objects that use the base column.

The @Where function is similar to @Select in that you can reuse a WHERE clause from an existing object.

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