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Author: alien
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Khóa học miễn phí Neo4j – Remove Clause nhận dự án làm có lương
Neo4j – Remove Clause
The REMOVE clause is used to remove properties and labels from graph elements (Nodes or Relationships).
The main difference between Neo4j CQL DELETE and REMOVE commands is −
- DELETE operation is used to delete nodes and associated relationships.
- REMOVE operation is used to remove labels and properties.
Removing a Property
You can remove a property of a node using MATCH along with the REMOVE clause.
Syntax
Following is the syntax to remove a property of a node using the REMOVE clause.
MATCH (node:label{properties . . . . . . . }) REMOVE node.property RETURN nodeExample
Before proceeding with the example, create a node named Dhoni as shown below.
CREATE (Dhoni:player {name: "MahendraSingh Dhoni", YOB: 1981, POB: "Ranchi"})Following is a sample Cypher Query to remove the above created node using the REMOVE clause.
MATCH (Dhoni:player {name: "MahendraSingh Dhoni", YOB: 1981, POB: "Ranchi"}) REMOVE Dhoni.POB RETURN DhoniTo execute the above query, carry out the following steps −
Step 1 − Open the Neo4j desktop App and start the Neo4j Server. Open the built-in browser app of Neo4j using the URL http://localhost:7474/ as shown in the following screenshot.
Step 2 − Copy and paste the desired query in the dollar prompt and press the play button (to execute the query) highlighted in the following screenshot.
Result
On executing, you will get the following result. Here, you can observe that the node named POB was deleted.
Removing a Label From a Node
Similar to property, you can also remove a label from an existing node using the remove clause.
Syntax
Following is the syntax to remove a label from a node.
MATCH (node:label {properties . . . . . . . . . . . }) REMOVE node:label RETURN nodeExample
Following is a sample Cypher Query to remove a label from an existing node using the remove clause.
MATCH (Dhoni:player {name: "MahendraSingh Dhoni", YOB: 1981, POB: "Ranchi"}) REMOVE Dhoni:player RETURN DhoniTo execute the above query, carry out the following steps −
Step 1 − Open the Neo4j desktop App and start the Neo4j Server. Open the built-in browser app of Neo4j using the URL http://localhost:7474/ as shown in the following screenshot.
Step 2 − Copy and paste the desired query in the dollar prompt and press the play button (to execute the query) highlighted in the following screenshot.
Result
On executing, you will get the following result. Here, you can observe that the label was deleted from the node.
Removing Multiple Labels
You can also remove multiple labels from an existing node.
Syntax
Following is the syntax to remove multiple labels from a node.
MATCH (node:label1:label2 {properties . . . . . . . . }) REMOVE node:label1:label2 RETURN nodeExample
Before proceeding with the example, create a node Ishant as shown below.
CREATE (Ishant:player:person {name: "Ishant Sharma", YOB: 1988, POB: "Delhi"})Following is a sample Cypher Query to remove multiple labels from a node.
MATCH (Ishant:player:person {name: "Ishant Sharma", YOB: 1988, POB: "Delhi"}) REMOVE Ishant:player:person RETURN IshantTo execute the above query, carry out the following steps −
Step 1 − Open the Neo4j desktop App and start the Neo4j Server. Open the built-in browser app of Neo4j using the URL http://localhost:7474/ as shown in the following screenshot.
Step 2 − Copy and paste the desired query in the dollar prompt and press the play button (to execute the query) highlighted in the following screenshot.
Result
On executing, you will get the following result. Here, you can observe that the specified labels were deleted from the node.
Khóa học lập trình tại Toidayhoc vừa học vừa làm dự án vừa nhận lương: Khóa học lập trình nhận lương tại trung tâm Toidayhoc
Khóa học miễn phí Neo4j CQL – Creating Nodes nhận dự án làm có lương
Neo4j CQL – Creating Nodes
As discussed, a node is a data/record in a graph database. You can create a node in Neo4j using the CREATE clause. This chapter teaches you how to −
- Create a single node
- Create multiple nodes
- Create a node with a label
- Create a node with multiple labels
- Create a node with properties
- Returning the created node
Creating a Single node
You can create a node in Neo4j by simply specifying the name of the node that is to be created along with the CREATE clause.
Syntax
Following is the syntax for creating a node using Cypher Query Language.
CREATE (node_name);
Note − Semicolon (;) is optional.
Example
Following is a sample Cypher Query which creates a node in Neo4j.
CREATE (sample)
To execute the above query, carry out the following steps −
Step 1 − Open the Neo4j desktop App and start the Neo4j Server as shown in the following screenshot.
Step 2 − Open your browser, copy paste the following URL in your address bar http://localhost:7474/. This will give you the built-in browser app of Neo4j with a dollar prompt as shown in the following screenshot.
Step 3 − Copy and paste the desired query in the dollar prompt and press the play button (to execute the query) highlighted in the following screenshot.
Result
On executing, you will get the following result.
Verification
To verify the creation of the node type, execute the following query in the dollar prompt.
MATCH (n) RETURN n
This query returns all the nodes in the database (we will discuss this query in detail in the coming chapters).
On executing, this query shows the created node as shown in the following screenshot.
Creating Multiple Nodes
The create clause of Neo4j CQL is also used to create multiple nodes at the same time. To do so, you need to pass the names of the nodes to be created, separated by a comma.
Syntax
Following is the syntax to create multiple nodes using the CREATE clause.
CREATE (node1),(node2)
Example
Following is a sample Cypher Query which creates multiple nodes in Neo4j.
CREATE (sample1),(sample2)
To execute the above query, carry out the following steps −
Step 1 − Open the Neo4j desktop App and start the Neo4j Server. Open the built-in browser app of Neo4j using the URL http://localhost:7474/ as shown in the following screenshot.
Step 2 − Copy and paste the desired query in the dollar prompt and press the play button (to execute the query) highlighted in the following screenshot.
Result
On executing, you will get the following result.
Verification
To verify the creation of the node, type and execute the following query in the dollar prompt.
MATCH (n) RETURN n
This query returns all the nodes in the database (we will discuss this query in detail in the coming chapters).
On executing, this query shows the created node as shown in the following screenshot.
Creating a Node with a Label
A label in Neo4j is used to group (classify) the nodes using labels. You can create a label for a node in Neo4j using the CREATE clause.
Syntax
Following is the syntax for creating a node with a label using Cypher Query Language.
CREATE (node:label)
Example
Following is a sample Cypher Query which creates a node with a label.
CREATE (Dhawan:player)
To execute the above query, carry out the following steps −
Step 1 − Open the Neo4j desktop App and start the Neo4j Server. Open the built-in browser app of Neo4j using the URL http://localhost:7474/ as shown in the following screenshot.
Step 2 − Copy and paste the desired query in the dollar prompt and press the play button (to execute the query) highlighted in the following screenshot.
Result
On executing, you will get the following result.
Verification
To verify the creation of the node, type and execute the following query in the dollar prompt.
MATCH (n) RETURN n
This query returns all the nodes in the database (we will discuss this query in detail in the coming chapters).
On executing, this query shows the created node as shown in the following screenshot.
Creating a Node with Multiple Labels
You can also create multiple labels for a single node. You need to specify the labels for the node by separating them with a colon “ : ”.
Syntax
Following is the syntax to create a node with multiple labels.
CREATE (node:label1:label2:. . . . labeln)
Example
Following is a sample Cypher Query which creates a node with multiple labels in Neo4j.
CREATE (Dhawan:person:player)
To execute the above query, carry out the following steps −
Step 1 − Open the Neo4j desktop App and start the Neo4j Server. Open the built-in browser app of Neo4j using the URL http://localhost:7474/ as shown in the following screenshot.
Step 2 − Copy and paste the desired query in the dollar prompt and press the play button (to execute the query) highlighted in the following screenshot.
Result
On executing, you will get the following result.
Verification
To verify the creation of the node, type and execute the following query in the dollar prompt.
MATCH (n) RETURN n
This query returns all the nodes in the database (we will discuss this query in detail in the coming chapters).
On executing, this query shows the created node as shown in the following screenshot.
Create Node with Properties
Properties are the key-value pairs using which a node stores data. You can create a node with properties using the CREATE clause. You need to specify these properties separated by commas within the flower braces “{ }”.
Syntax
Following is the syntax to create a node with properties.
CREATE (node:label { key1: value, key2: value, . . . . . . . . . })
Example
Following is a sample Cypher Query which creates a node with properties.
CREATE (Dhawan:player{name: "Shikar Dhawan", YOB: 1985, POB: "Delhi"})
To execute the above query, carry out the following steps −
Step 1 − Open the Neo4j desktop App and start the Neo4j Server. Open the built-in browser app of Neo4j using the URL http://localhost:7474/ as shown in the following screenshot.
Step 2 − Copy and paste the desired query in the dollar prompt and press the play button (to execute the query) highlighted in the following screenshot.
Result
On executing, you will get the following result.
Verification
To verify the creation of the node, type and execute the following query in the dollar prompt.
MATCH (n) RETURN n
This query returns all the nodes in the database (we will discuss this query in detail in the coming chapters).
On executing, this query shows the created node as shown in the following screenshot.
Returning the Created Node
Throughout the chapter, we used the MATCH (n) RETURN n query to view the created nodes. This query returns all the existing nodes in the database.
Instead of this, we can use the RETURN clause with CREATE to view the newly created node.
Syntax
Following is the syntax to return a node in Neo4j.
CREATE (Node:Label{properties. . . . }) RETURN Node
Example
Following is a sample Cypher Query which creates a node with properties and returns it.
CREATE (Dhawan:player{name: "Shikar Dhawan", YOB: 1985, POB: "Delhi"}) RETURN Dhawan
To execute the above query, carry out the following steps −
Step 1 − Open the Neo4j desktop App and start the Neo4j Server. Open the built-in browser app of Neo4j using the URL http://localhost:7474/ as shown in the following screenshot.
Step 2 − Copy and paste the desired query in the dollar prompt and press the play button (to execute the query) highlighted in the following screenshot.
Result
On executing, you will get the following result.
Khóa học lập trình tại Toidayhoc vừa học vừa làm dự án vừa nhận lương: Khóa học lập trình nhận lương tại trung tâm Toidayhoc
