Format, Parameters

WHERE can keep the rows of data in the data streams that meet the conditions, and discard those that do not meet the conditions.

Syntax:

• Format 1: where <condition>
• Format 2: where <query> (Under development)
• Parameters: see table below
• Affected columns: all aliases and homologous columns from <condition> and <query>; non-homologous aliases will be trimmed to the shortest length so that they can become homologous columns before calculation

WHERE can seperate some filtering conditions from Ultipa Filter to improve UQL readability; it can also realize subgraph queries as complex as graph() command.

Analysis

find().nodes({shape == "square"}) as n1
find().nodes({shape == "round"}) as n2
where n1.color == n2.color
return n1, n2

In the UQL statement above, WHERE trims the two non-homologous columns outputted from 2 node queries to the shortest length，3 rows, then filter each row

where <condition>

Example: find three-step transfer paths from Card CA001 to Card CA002, with two intermediate cards in the paths containing at least one card whose level is 5

n({_id == "CA001"}).e().n({@card} as n1)
  .e().n({@card} as n2)
  .e().n({_id == "CA002"}) as p
where n1.level == 5 || n2.level == 5
return p{*}

where <query> (Under Development)

Example: find an intermediate card with alias 'agent' that satisfies conditions as shown in the image below: Card CA002 transfers money to Card CA001 via agent; agent is a neighbor to Card CA003 within 2 hops

n({_id == "CA002"}).re().n({@card} as agent).re().n({_id == "CA001"})
where n(agent).e()[*:2].n({_id == "CA003"})
return agent{*}

Analysis: WHERE further filters data columns "agent": it judges if the shortest paths from "agent" to Card CA003 exist, if true, then it passes "agent" to later "return"

The example above can be put in a subgraph template as shown below:

graph([
  n({_id == "CA002"}).re().n({@card} as agent).re().n({_id == "CA001"}),
  n(agent).e()[*:2].n({_id == "CA003"})
])
return agent{*}