Space Race/Relationships Tutorial - Revision history

ChrisHouston at 08:43, 9 December 2019

2019-12-09T08:43:33Z

← Older revision		Revision as of 08:43, 9 December 2019
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	{{Acknowledgements}}		{{Acknowledgements}}

ChrisHouston at 12:14, 1 December 2019

2019-12-01T12:14:00Z

← Older revision		Revision as of 12:14, 1 December 2019
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	<p>Relationships are the most powerful part of graph-based databases. While some of the functionality these provide is possible under SQL using join tables for many to many relationships, certain queries can be constructed which would require many joins in SQL.</p>		<p>Relationships are the most powerful part of graph-based databases. While some of the functionality these provide is possible under SQL using join tables for many to many relationships, certain queries can be constructed which would require many joins in SQL. A good example is the number of connections required to link one node to another.</p>
	<p>All relationships in Neo4j are directional, that is they have a start and end node. They can only possess a single <code>TYPE</code>, rather than multiple labels, but they can also possess properties similar to nodes</p>		<p>All relationships in Neo4j are directional, that is they have a start and end node. They can only possess a single <code>TYPE</code>, rather than multiple labels, but they can also possess properties similar to nodes</p>

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	[http://nosqlzoo.net/mw/visproject/visualisation.php Click here for 3d graph visualisation]		[http://nosqlzoo.net/mw/visproject/visualisation.php Click here for 3d graph visualisation]


	==Relationship types==		==Relationship types==
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	<p>The <code>Type()</code> function can return the type of a relationship</p>		<p>The <code>Type()</code> function can return the type of a relationship</p>
	<p class='strong'>Return the type of the relationship between Astronaut and Mission</p>		<p class='strong'>Return the type of the relationship between Astronaut and Mission</p>
	<pre class="def"><nowiki>MATCH(n:Astronaut)-[r]->(c:Country) RETURN type(r);</nowiki>		<pre class="def"><nowiki>MATCH(:Astronaut)-[r]->(:Country) RETURN DISTINCT type(r);</nowiki>
	</pre>		</pre>
	<pre class="ans"><nowiki>MATCH(n:Astronaut)-[r]->(m:Mission) RETURN type(r);</nowiki>		<pre class="ans"><nowiki>MATCH(:Astronaut)-[r]->(:Mission) RETURN DISTINCT type(r);</nowiki>
	</pre>		</pre>
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			==Saturn V Missions==
			<div class="q nonum" data-lang="neo4j">
			<p>Aggregate functions can also be used on the result of relationships queries</p>
			<p class='strong'>Show how many missions were launched on the Saturn V.</p>
			<pre class="def"><nowiki>MATCH(n:LaunchVehicle{name:"Saturn V"})RETURN DISTINCT n; </nowiki>
			</pre>
			<pre class="ans"><nowiki>MATCH(:LaunchVehicle{name:"Saturn V"})<-[r:LAUNCHED_ON]-(:Mission) RETURN count(r);</nowiki>
			</pre>
			</div>

	{{Acknowledgements}}		{{Acknowledgements}}

ChrisHouston at 09:40, 29 November 2019

2019-11-29T09:40:59Z

← Older revision		Revision as of 09:40, 29 November 2019
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	<p>Numerous relationships can be strung together. <code>DISTINCT</code> can be used to only display a result once if that node is linked to multiple times</p>		<p>Numerous relationships can be strung together. <code>DISTINCT</code> can be used to only display a result once if that node is linked to multiple times</p>
	<p class='strong'>Show the names of everyone that James Lovell flew with.</p>		<p class='strong'>Show the names of everyone that James Lovell flew with.</p>
	<pre class="def"><nowiki>MATCH(n:Astronaut{surname:"Armstrong"})-[:CREWED]->(a:Mission)<-[:CREWED]-(m:Astronaut) RETURN DISTINCT m.surname, m.first_name </nowiki>		<pre class="def"><nowiki>MATCH(n:Astronaut{surname:"Armstrong"})-[:CREWED]->(a:Mission)<-[:CREWED]-(m:Astronaut) RETURN DISTINCT m.surname, m.first_name; </nowiki>
	</pre>		</pre>
	<pre class="ans"><nowiki>MATCH(n:Astronaut{surname:"Lovell"})-[:CREWED]->(a:Mission)<-[:CREWED]-(m:Astronaut) RETURN DISTINCT m.surname, m.first_name</nowiki>		<pre class="ans"><nowiki>MATCH(n:Astronaut{surname:"Lovell"})-[:CREWED]->(a:Mission)<-[:CREWED]-(m:Astronaut) RETURN DISTINCT m.surname, m.first_name;</nowiki>
	</pre>		</pre>
	</div>		</div>

ChrisHouston at 09:38, 29 November 2019

2019-11-29T09:38:57Z

← Older revision		Revision as of 09:38, 29 November 2019
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	<div class="q nonum" data-lang="neo4j">		<div class="q nonum" data-lang="neo4j">
	<p>Numerous relationships can be strung together. <code>DISTINCT</code> can be used to only display a result once if that node is linked to multiple times</p>		<p>Numerous relationships can be strung together. <code>DISTINCT</code> can be used to only display a result once if that node is linked to multiple times</p>
	<p class='strong'>Show the names of everyone that James Lovell flew with ~~and the mission he flew with them on~~.</p>		<p class='strong'>Show the names of everyone that James Lovell flew with.</p>
	<pre class="def"><nowiki>MATCH(n:Astronaut{surname:"Armstrong"})-[:CREWED]->(a:Mission)<-[:CREWED]-(m:Astronaut) RETURN DISTINCT m.surname, m.first_name </nowiki>		<pre class="def"><nowiki>MATCH(n:Astronaut{surname:"Armstrong"})-[:CREWED]->(a:Mission)<-[:CREWED]-(m:Astronaut) RETURN DISTINCT m.surname, m.first_name </nowiki>
	</pre>		</pre>

ChrisHouston at 09:38, 29 November 2019

2019-11-29T09:38:27Z

@@ Line 1: / Line 1: @@
 <p>Relationships are the most powerful part of graph-based databases. While some of the functionality these provide is possible under SQL using join tables for many to many relationships, certain queries can be constructed which would require many joins in SQL.</p>
-<p>All relationships in Neo4j are directional, that is they have a start and end node. As well as being also able to possess labels, they can also possess properties similar to nodes</p>
+<p>All relationships in Neo4j are directional, that is they have a start and end node. They can only possess a single <code>TYPE</code>, rather than multiple labels, but they can also possess properties similar to nodes</p>
 == Visualisation ==
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 [http://nosqlzoo.net/mw/visproject/visualisation.php Click here for 3d graph visualisation]
 ==Born in Russia==
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 </pre>
 </div>
 {{Acknowledgements}}

ChrisHouston: Created page with "
Relationships are the most powerful part of graph-based databases. While some of the functionality these provide is possible under SQL using join tables for many to many re..."

2019-11-29T09:01:24Z

Created page with "Relationships are the most powerful part of graph-based databases. While some of the functionality these provide is possible under SQL using join tables for many to many re..."

New page

Relationships are the most powerful part of graph-based databases. While some of the functionality these provide is possible under SQL using join tables for many to many relationships, certain queries can be constructed which would require many joins in SQL.
All relationships in Neo4j are directional, that is they have a start and end node. As well as being also able to possess labels, they can also possess properties similar to nodes

== Visualisation ==

[http://nosqlzoo.net/mw/visproject/visualisation.php Click here for 3d graph visualisation]

==Born in Russia==
<div class="q nonum" data-lang="neo4j">
The item in <code>[]</code> represents a relationship between nodes, in this case the relationship possessing the label "BORN_IN"
Note the <code>(startNode)-[:LABEL_NAME]->(endNode)</code> format. The direction the arrow points shows which node is the end point.
It is perfectly valid to express this relationship as <code>(endNode)<-[:LABEL_NAME]-(startNode)</code>
If you are not concerned about the direction of the relationships, you can also <code>MATCH</code> based on <code>(node1)-[:LABEL_NAME]-(node2)</code>
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
<pre class="def"><nowiki>MATCH(n:Astronaut)-[:BORN_IN]->(c:Country) WHERE c.abbrev ='USA' RETURN n.surname, c.name;</nowiki>
</pre>
<pre class="ans"><nowiki>MATCH(n:Astronaut)-[:BORN_IN]->(c:Country) WHERE c.abbrev= 'RU' RETURN n.surname, c.name;</nowiki>
</pre>
</div>

{{Acknowledgements}}

Space Race/Relationships Tutorial - Revision history

ChrisHouston at 08:43, 9 December 2019

ChrisHouston at 12:14, 1 December 2019

ChrisHouston at 09:40, 29 November 2019

ChrisHouston at 09:38, 29 November 2019

ChrisHouston at 09:38, 29 November 2019

ChrisHouston: Created page with "Relationships are the most powerful part of graph-based databases. While some of the functionality these provide is possible under SQL using join tables for many to many re..."

ChrisHouston: Created page with "
Relationships are the most powerful part of graph-based databases. While some of the functionality these provide is possible under SQL using join tables for many to many re..."