Conditional results

Question

Hi there.
I'm trying to build a query that return different items depending on a boolean parameter. Depending of it value, it will join 2 relationalDB tables from different Databases or not, but conditional expressions are limited to mappings. I look for a solution on W3C XQuery/XPath drafts and on a few books but i can't see the solution.
Must i divide it in 2 queries instead making a big one?
Next step on my project is introducing an XML DB and more crossed joins will be used?
I need to make them for finishing my end-of-career project so please help.

Answer 1

Wouldn't it be much clearer if you simply wrote two different queries - instead of one query with different inputs and different outputs that did two different things?
Otherwise, you could define a target schema, under the root you have two elements a, b which are both 'repeatable', create the mappings etc. to 'a', and create the mappings etc. to 'b'. Then create a condition $parm eq xf:true() and scope it to element a, and another condition $parm eq xf:false() and scope it to b. That should do it. (on the Conditions tab, select 'Advanced View' to allows 'scoping').
<results>
     for $PB_BB.CUSTOMER_1 in document("PB-BB")/db/CUSTOMER
     where ($#cid of type xs:string eq $PB_BB.CUSTOMER_1/CUSTOMER_ID)
     and ($#use_a of type xs:boolean eq xf:true())
     return
     <a>{ xf:data($PB_BB.CUSTOMER_1/FIRST_NAME) }</a>
     for $PB_BB2.CUSTOMER_2 in document("PB-BB")/db/CUSTOMER
     where ($#cid of type xs:string eq $PB_BB2.CUSTOMER_2/CUSTOMER_ID)
     and ($#use_a of type xs:boolean eq xf:false())
     return
     <b>{ xf:data($PB_BB2.CUSTOMER_2/LAST_NAME) }</b>
</results>
- Mike