Difference between revisions of "Space Race/MATCH Tutorial"

Use MATCH and RETURN to return nodes. Use : to specify what label(s) you wish the returned nodes to have. Not specifying any label will return ALL nodes

Show Institutions instead of Astronauts

MATCH(n:Astronaut) RETURN n;

MATCH(n:Institution) RETURN n; 

Use WHERE to specify conditions and the . operator to access individual properties of a node.

The item in [] represents a relationship between nodes, in this case the relationship possessing the label "BORN_IN"

Show the Surnames of Astronauts born in Russia, and the full name of Russia rather than the USA. Hint: Use the ISO 3166-1 Alpha-2 code in all caps

MATCH(n:Astronaut)-[:BORN_IN]->(c:Country) WHERE c.abbrev ='USA' RETURN n.surname, c.name;

MATCH(n:Astronaut)-[:BORN_IN]->(c:Country) WHERE c.abbrev= 'RU' RETURN n.surname, c.name;

When simply matching based on properties of a node, use the {} with the format {property:value}

Return Neil Armstrong's date of birth

MATCH(n:Astronaut{surname:"Gagarin",first_name:"Yuri"})RETURN n.dob;

MATCH(n:Astronaut{surname:"Armstrong",first_name:"Neil"})RETURN n.dob;

ORDER BY works similarly to SQL, defaulting to ordering from low to high value. Adding DESC instead orders the result in descending order

Return the names of the Astronauts ordered by their date of birth from earlier to later

MATCH(n:Astronaut) RETURN n.first_name, n.surname ORDER BY n.surname;

MATCH(n:Astronaut) RETURN n.first_name, n.surname ORDER BY n.dob;

In Neo4j, rather empty than properties being assigned a value of NULL like in SQL, properties which are not assigned a value do not exist at all

This can be checked using the EXISTS() comparator

Return the nicknames of the Astronauts who have them in reverse alphabetical order

MATCH(n:Astronaut)WHERE EXISTS(n.middle_names) RETURN n.middle_names; 

MATCH(n:Astronaut)WHERE EXISTS(n.nickname) RETURN n.nickname ORDER BY n.nickname DESC;