mirror of
https://github.com/adambard/learnxinyminutes-docs.git
synced 2024-12-23 17:41:41 +00:00
[cypher/en] Fix syntax for code blocks (#2706)
This commit is contained in:
parent
c5bf612743
commit
8eb6ce41fe
@ -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**).
|
||||||
|
Loading…
Reference in New Issue
Block a user