CouchDB: representing NVL() in view

Question

I'm writing a Couchdb _design document for the SQL command below:

SELECT NVL(MAX(NVL(VERSION,0)),0)+1 FROM pricelistdocs WHERE 
PRICE_LIST_ID = ?  AND DELETION_FLAG = 0;

I came up with a _design view function below while run and return values but I doubt if the correct and fulfills expectation of the above SQL command.

function(doc){
 if(doc.PRICE_LIST_ID == "110011"  && doc.DELETION_FLAG == "0" ){
   emit(doc._id, doc.VERSION);
 }
}

Please how can I add the NVL() and MAX function to my _design view document above. Any infortiom or clue is appreciated. Thank you for your time.

Answer 1

You can write your own NVL function by checking for the existance of a field and returning 0 if it does not exist.

For the max functionality, you have to add a reduce function to your view. If you just want to get the maximum, "reduce": "_max" will do, which is a built in reduce function.