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Space Race/MATCH Tutorial

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< Space Race
Revision as of 08:47, 29 November 2019 by ChrisHouston (talk | contribs)
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Visualisation

Click here for 3d graph visualisation

Institutions

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; 

Neil Armstrong's Birthday

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;

The Young and Old

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;

Nicknames

In Neo4j, rather than empty 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() function

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;

Acknowledgements

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