Delete

Overview

The delete() statement removes nodes or edges that meet specified conditions.

Syntax
// Deletes isolated nodes
delete().nodes(<filter?>).nodetach()

// Deletes nodes along with any edges connected to them
delete().nodes(<filter?>).detach()

// Deletes edges
delete().edges(<filter?>)

An edge cannot exist if any of its endpoints is removed from the graph. By default, UQL does not allow to delete a node while it still has edges connected to it.

However, you can use the method detach() or nodetach().force() to enable the deletion of nodes along with their connected edges. For example, when node B is deleted, edges 1, 2 and 4 will also be deleted.

Example Graph

To create the graph, execute the following UQL queries sequentially in an empty graphset:

UQL
create().node_schema("user").edge_schema("follow")
create().node_property(@user, "name").node_property(@user, "age", int32).edge_property(@follow, "time", datetime)
insert().into(@user).nodes([{_id:"U001", name:"Jason", age:30}, {_id:"U002", name:"Tim"}, {_id:"U003", name:"Grace", age:25}, {_id:"U004", name:"Ted", age:26}, {_id:"U005", name:"Kyle", age:21}])
insert().into(@follow).edges([{_from:"U004", _to:"U001", time:"2021-9-10"}, {_from:"U003", _to:"U001", time:"2020-3-12"}, {_from:"U004", _to:"U002", time:"2023-7-30"}])

Deleting Isolated Nodes

To delete the isolated node whose name is Kyle:

UQL
delete().nodes({name == "Kyle"})

The delete().nodes() query can only delete isolated nodes, if any node specified has connected edges, an error will be thrown, and no nodes will be deleted.

Deleting Any Nodes

To delete the node whose name is Grace along with its connected edges:

UQL
delete().nodes({name == "Grace"}).detach()

To delete all nodes along with all edges:

UQL
delete().nodes().detach()

Deleting Edges

To delete @follow edges:

UQL
delete().edges({@follow})

Limiting the Amount to Delete

To limit the number of nodes or edges to delete, first retrieve the data from the database using statements like find(), then apply the LIMIT statement to keep only the first N records before passing the alias to the delete() statement.

To delete any two edges:

UQL
find().edges() as e limit 2
delete().edges(e)
return e{*}

Result: e