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Neo4j

CONSTRAINT

CREATE CONSTRAINT ON (p:Person)
       ASSERT p.name IS UNIQUE

Create a unique property constraint on the label Person and property name. If any other node with that label is updated or created with a name that already exists, the write operation will fail. This constraint will create an accompanying index.

CREATE CONSTRAINT uniqueness ON (p:Person)
       ASSERT p.age IS UNIQUE

Create a unique property constraint on the label Person and property age with the name uniqueness. If any other node with that label is updated or created with a age that already exists, the write operation will fail. This constraint will create an accompanying index.

CREATE CONSTRAINT ON (p:Person)
       ASSERT p.surname IS UNIQUE
       OPTIONS {indexProvider: 'native-btree-1.0'}

Create a unique property constraint on the label Person and property surname with the index provider native-btree-1.0 for the accompanying index.

CREATE CONSTRAINT ON (p:Person)
       ASSERT p.name IS NOT NULL

(★) Create a node property existence constraint on the label Person and property name, throws an error if the constraint already exists. If a node with that label is created without a name, or if the name property is removed from an existing node with the Person label, the write operation will fail.

CREATE CONSTRAINT node_exists IF NOT EXISTS ON (p:Person)
       ASSERT p.name IS NOT NULL

(★) If a node property existence constraint on the label Person and property name or any constraint with the name node_exists already exist then nothing happens. If no such constraint exists, then it will be created.

CREATE CONSTRAINT ON ()-[l:LIKED]-()
       ASSERT l.when IS NOT NULL

(★) Create a relationship property existence constraint on the type LIKED and property when. If a relationship with that type is created without a when, or if the when property is removed from an existing relationship with the LIKED type, the write operation will fail.

CREATE CONSTRAINT relationship_exists ON ()-[l:LIKED]-()
       ASSERT l.since IS NOT NULL

(★) Create a relationship property existence constraint on the type LIKED and property since with the name relationship_exists. If a relationship with that type is created without a since, or if the since property is removed from an existing relationship with the LIKED type, the write operation will fail.

SHOW UNIQUE CONSTRAINTS YIELD *

List all unique constraints.

CREATE CONSTRAINT ON (p:Person)
      ASSERT (p.firstname, p.surname) IS NODE KEY

(★) Create a node key constraint on the label Person and properties firstname and surname. If a node with that label is created without both firstname and surname or if the combination of the two is not unique, or if the firstname and/or surname labels on an existing node with the Person label is modified to violate these constraints, the write operation will fail.

CREATE CONSTRAINT node_key ON (p:Person)
      ASSERT (p.name, p.surname) IS NODE KEY

(★) Create a node key constraint on the label Person and properties name and surname with the name node_key. If a node with that label is created without both name and surname or if the combination of the two is not unique, or if the name and/or surname labels on an existing node with the Person label is modified to violate these constraints, the write operation will fail.

CREATE CONSTRAINT node_key_with_config ON (p:Person)
      ASSERT (p.name, p.age) IS NODE KEY
      OPTIONS {indexConfig: {`spatial.wgs-84.min`: [-100.0, -100.0], `spatial.wgs-84.max`: [100.0, 100.0]}}

(★) Create a node key constraint on the label Person and properties name and age with the name node_key_with_config and given spatial.wgs-84 settings for the accompanying index. The other index settings will have their default values.

DROP CONSTRAINT uniqueness

Drop the constraint with the name uniqueness, throws an error if the constraint does not exist.

DROP CONSTRAINT uniqueness IF EXISTS

Drop the constraint with the name uniqueness if it exists, does nothing if it does not exist.

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