Graph Queries Filtering

You can use RQL keywords and operators within a graph query node/edge clause, to narrow query results down.

• where can be used within data node and edge clauses, to condition the query.
• select can be used within edge clauses, to choose wanted details of filtered results .
• Operators like and and or can complement where within data-node and edge clauses.
  (You can place these operators between query sections as well. Learn more about it here: Multi-Section Search Patterns)

Sample queries included in this article use only data that is available in the Northwind sample database, so you may easily try them out.

• In this page:
  • Using where To Filter Results
  • Using select To Choose Filtered Results
  • Using where With or
  • Using where With and
  • Additional Filtering Examples

Filtering

You can filter data within data-node and edge clauses, using RQL.

Using where To Filter Results

where can be used within both data-node and edge clauses.
Here, for example, we retrieve only big orders from the Orders collection:

match 
  (Orders as orders 
     where Freight > 5)

Using select To Choose Filtered Results

select can be used alongside where, within an edge clause, to select details of filtered data.

In the following example, we're looking for paths between orders and products with a discount:

match 
  (Orders as orders)-  
  [Lines as cheap 
     where Discount >= 0.25 
         select Product]->
  (Products as products)

• Query Flow:
  • The edge clause uses where to search each order's Lines construct.
    Only edges of products with a high-enough discount will be used.
  • Then, select is used to pick the actual edge - the ID of a product profile.

You **cannot** use `select` within a data-node clause.

Note: Do not confuse the current usage of select with the implementation of the same keyword to project data.

Using where With or

The following query uses where along with or, to find products of two different categories.

• Implicit
• Explicit

match
  (Products as products)-
  [Category as category]->
  (Categories as categories 
      where Name="Confections" 
          or Name="Condiments")

with {from Products} as products
with edges (Category) as category
with {from Categories 
  where Name="Confections" 
      or Name="Condiments"} as categories
match 
  (products)-
  [category]->
  (categories)

Using where With and

The following query uses where along with and, to find products in a chosen price range.

match
  (Orders as orders) -
  [Lines as lines 
      select Product]->  
  (Products as products 
      where (PricePerUnit < 20 
          and PricePerUnit > 15))

select orders.Company as company, products.Name as name

• Filtering the products (the destination nodes) also determine which orders (the origin nodes) would be included in the results.

Additional Filtering Examples

Let's look at a few more examples to filtering within query clauses.

• Here, we query the relations between orders, products and suppliers.
  We look for products whose discount is low and price is high, because we want to renegotiate such deals.
  We limit the results to suppliers whose contact is also the owner, so we'd have who to negotiate with.

match
  (Orders as orders 
      where (Lines.PricePerUnit > 50 
          and Lines.Discount < 0.10))-
  [Lines as negotiateThisProduct 
      select Product]->
  (Products as products)-
  [Supplier as contactIsOwner]->
  (Suppliers as salesrep 
      where Contact.Title = "Owner")

select
  id(orders) as Pricy, 
  products.QuantityPerUnit as Negotiate, 
  salesrep.Name as Supplier,
  salesrep.Contact.Name as Contact

• Here is an example for the gradual development of a modular query, and filters included in it.
  • First, we limit the retrieval of orders to ones ordered from Brazil.

match
  (Orders as orders 
      where (ShipTo.Country = "Brazil"))-
  [Lines as lines 
      select Product]->  
  (Products as products)

• Then we add another data layer by including Suppliers in our query, and create another filter to include in the results only french suppliers.

match
  (Orders as orders 
      where (ShipTo.Country = "Brazil"))-
  [Lines as lines 
      select Product]->  
  (Products as products)-
  [Supplier as supplier]-> 
  (Suppliers as suppliers 
      where Address.Country = "France")