Constraints Exists

[kadam_infotech]

what is difference between is not null and exists constraint in neo4j are they same also was trying to create below but getting error :

Invalid input 'n': expected whitespace, comment or UNIQUE (line 1, column 70 (offset: 69))
"CREATE CONSTRAINT constraint_name ON (book:Book) ASSERT book.isbn is not null"

Any guess why its giving error

[giuseppe_villan · Accepted solution]

Yes, you're right. they are equivalent.
It's just a matter of syntax. that is, up to neo4j 4.2, the syntax with "IS NOT NULL" was not interpreted by cypher.
Since version 4.3 this syntax has been added, as you can see here:

Neo4j Graph Database Platform

Deprecations, additions and compatibility - Neo4j Cypher Manual

Cypher is a language that is constantly evolving.

Obviously "IS NOT NULL" and "exists" coincide.