search dataset on the basis of database 

This is the basic code for searching a dataset

`quandl.search("crude oil", { format: "xml" }, function(err, response){
console.log(err);
console.log(response);
})`

It will result in dataset corresponding to crude oil in all the databases.

How we can make a search for a dataset in particular database say yahoo.
for example search crude oil in yahoo or ZEP database
