[cypher/en] Fix syntax for code blocks (#2706)

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Théo Gauchoux 2017-04-13 17:21:23 +02:00 committed by ven
parent c5bf612743
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@ -11,34 +11,37 @@ This tutorial assumes that you already know graph concepts like nodes and relati
[Read more here.](https://neo4j.com/developer/cypher-query-language/) [Read more here.](https://neo4j.com/developer/cypher-query-language/)
`// There is just single-line comments in Cypher`
Nodes Nodes
--- ---
**Represents a record in a graph.** **Represents a record in a graph.**
**`()`** It's an empty *node*, to indicate that there is a *node*, but it's not relevant for the query. ```()```
It's an empty *node*, to indicate that there is a *node*, but it's not relevant for the query.
**`(n)`** It's a *node* refered by the variable **n**, reusable in the query. It begins with lowercase and uses camelCase. ```(n)```
It's a *node* refered by the variable **n**, reusable in the query. It begins with lowercase and uses camelCase.
**`(p:Person)`** You can add a *label* to your node, here **Person**. It's like a type / a class / a category. It begins with uppercase and uses camelCase. ```(p:Person)```
You can add a *label* to your node, here **Person**. It's like a type / a class / a category. It begins with uppercase and uses camelCase.
**`(p:Person:Manager)`** A node can have many *labels*. ```(p:Person:Manager)```
A node can have many *labels*.
**`(p:Person {name : 'Théo Gauchoux', age : 22})`** A node can have some *properties*, here **name** and **age**. It begins with lowercase and uses camelCase. ```(p:Person {name : 'Théo Gauchoux', age : 22})```
A node can have some *properties*, here **name** and **age**. It begins with lowercase and uses camelCase.
The types allowed in properties : The types allowed in properties :
* Numeric
* Boolean
* String
* List of previous primitive types
**Warning : there isn't datetime property in Cypher ! You can use String with a specific pattern or a Numeric from a specific date.** - Numeric
- Boolean
- String
- List of previous primitive types
**`p.name`** You can access to a property with the dot style. *Warning : there isn't datetime property in Cypher ! You can use String with a specific pattern or a Numeric from a specific date.*
```p.name```
You can access to a property with the dot style.
Relationships (or Edges) Relationships (or Edges)
@ -46,13 +49,17 @@ Relationships (or Edges)
**Connects two nodes** **Connects two nodes**
**`[:KNOWS]`** It's a *relationship* with the *label* **KNOWS**. It's a *label* as the node's label. It begins with uppercase and use UPPER_SNAKE_CASE. ```[:KNOWS]```
It's a *relationship* with the *label* **KNOWS**. It's a *label* as the node's label. It begins with uppercase and use UPPER_SNAKE_CASE.
**`[k:KNOWS]`** The same *relationship*, refered by the variable **k**, reusable in the query, but it's not necessary. ```[k:KNOWS]```
The same *relationship*, refered by the variable **k**, reusable in the query, but it's not necessary.
**`[k:KNOWS {since:2017}]`** The same *relationship*, with *properties* (like *node*), here **since**. ```[k:KNOWS {since:2017}]```
The same *relationship*, with *properties* (like *node*), here **since**.
**`[k:KNOWS*..4]`** It's a structural information to use in a *path* (seen later). Here, **\*..4** says "Match the pattern, with the relationship **k** which be repeated between 1 and 4 times. ```[k:KNOWS*..4]```
It's a structural information to use in a *path* (seen later). Here, **\*..4** says "Match the pattern, with the relationship **k** which be repeated between 1 and 4 times.
Paths Paths
@ -60,13 +67,17 @@ Paths
**The way to mix nodes and relationships.** **The way to mix nodes and relationships.**
**`(a:Person)-[:KNOWS]-[b:Person]`** A path describing that **a** and **b** know each other. ```(a:Person)-[:KNOWS]-[b:Person]```
A path describing that **a** and **b** know each other.
**`(a:Person)-[:MANAGES]->[b:Person]`** A path can be directed. This path describes that **a** is the manager of **b**. ```(a:Person)-[:MANAGES]->[b:Person]```
A path can be directed. This path describes that **a** is the manager of **b**.
**`(a:Person)-[:KNOWS]-[b:Person]-[:KNOWS]-[c:Person]`** You can chain multiple relationships. This path describes the friend of a friend. ```(a:Person)-[:KNOWS]-[b:Person]-[:KNOWS]-[c:Person]```
You can chain multiple relationships. This path describes the friend of a friend.
**`(a:Person)-[:MANAGES]->[b:Person]-[:MANAGES]->[c:Person]`** A chain can also be directed. This path describes that **a** is the boss of **b** and the big boss of **c**. ```(a:Person)-[:MANAGES]->[b:Person]-[:MANAGES]->[c:Person]```
A chain can also be directed. This path describes that **a** is the boss of **b** and the big boss of **c**.
Patterns often used (from Neo4j doc) : Patterns often used (from Neo4j doc) :
@ -85,6 +96,7 @@ path = shortestPath( (user)-[:KNOWS*..5]-(other) )
``` ```
Create queries Create queries
--- ---
@ -148,6 +160,7 @@ WHERE a.name = "Jacquie" AND b.name = "Michel"
CREATE (a)-[:KNOWS]-(b) CREATE (a)-[:KNOWS]-(b)
``` ```
Update queries Update queries
--- ---
@ -179,6 +192,7 @@ WHERE p.name = "Théo Gauchoux"
SET p:Internship SET p:Internship
``` ```
Delete queries Delete queries
--- ---
@ -212,17 +226,24 @@ DELETE n, r
``` ```
*Seriously, it's the `rm -rf /` of Cypher !* *Seriously, it's the `rm -rf /` of Cypher !*
Other useful clauses Other useful clauses
--- ---
**`PROFILE`** Before a query, show the execution plan of it. ```PROFILE```
**`COUNT(e)`** Count entities (nodes or relationships) matching **e**. Before a query, show the execution plan of it.
**`LIMIT x`** Limit the result to the x first results.
```COUNT(e)```
Count entities (nodes or relationships) matching **e**.
```LIMIT x```
Limit the result to the x first results.
Special hints Special hints
--- ---
* You can execute a Cypher script stored in a **.cql** file directly in Neo4j (it's an import). However, you can't have multiple statements in this file (separed by **;**). - There is just single-line comments in Cypher, with double-slash : // Comments
* Use the Neo4j shell to write Cypher, it's really awesome. - You can execute a Cypher script stored in a **.cql** file directly in Neo4j (it's an import). However, you can't have multiple statements in this file (separed by **;**).
* The Cypher will be the standard query language for all graph databases (known as **OpenCypher**). - Use the Neo4j shell to write Cypher, it's really awesome.
- The Cypher will be the standard query language for all graph databases (known as **OpenCypher**).