Category: neo4j

Neo4j – Merge Command ”; Previous Next MERGE command is a combination of CREATE command and MATCH command. Neo4j CQL MERGE command searches for a given pattern in the graph. If it exists, then it returns the results. If it does NOT exist in the graph, then it creates a new node/relationship and returns the results. In this chapter you are going to learn how to − Merge a node with label Merge a node with properties OnCreate and OnMatch Merge a relationship Syntax Following is the syntax for the MERGE command. MERGE (node: label {properties . . . . . . . }) Before proceeding to the examples in this section, create two nodes in the database with labels Dhawan and Ind. Create a relationship of type “BATSMAN_OF” from Dhawan to Ind as shown below. CREATE (Dhawan:player{name: “Shikar Dhawan”, YOB: 1985, POB: “Delhi”}) CREATE (Ind:Country {name: “India”}) CREATE (Dhawan)-[r:BATSMAN_OF]->(Ind) Merging a Node with a Label You can merge a node in the database based on the label using the MERGE clause. If you try to merge a node based on the label, then Neo4j verifies whether there exists any node with the given label. If not, the current node will be created. Syntax Following is the syntax to merge a node based on a label. MERGE (node:label) RETURN node Example 1 Following is a sample Cypher Query which merges a node into Neo4j (based on label). When you execute this query, Neo4j verifies whether there is any node with the label player. If not, it creates a node named “Jadeja” and returns it. If, there exists any node with the given label, Neo4j returns them all. MERGE (Jadeja:player) RETURN Jadeja 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. Since you have already created a node named “Dhawan” with the label “player” in the database, Neo4j returns it as shown in the following screenshot. Example 2 Now, try to merge a node named “CT2013” with a label named Tournament. Since there are no nodes with this label, Neo4j creates a node with the given name and returns it. MERGE (CT2013:Tournament{name: “ICC Champions Trophy 2013”}) RETURN CT2013, labels(CT2013) 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. As discussed, since there is no node with the given label (Tournament). Neo4j creates and returns the specified node as shown in the following screenshot. Merging a Node with Properties You can also merge a node with a set of properties. If you do so, Neo4j searches for an equal match for the specified node, including the properties. If it doesn’t find any, it creates one. Syntax Following is the syntax to merge a node using properties. MERGE (node:label {key1:value, key2:value, key3:value . . . . . . . . }) Example Following is a sample Cypher Query to merge a node using properties. This query tries to merge the node named “jadeja” using properties and label. Since there is no such node with the exact label and properties, Neo4j creates one. MERGE (Jadeja:player {name: “Ravindra Jadeja”, YOB: 1988, POB: “NavagamGhed”}) RETURN Jadeja 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. As discussed, since there are no nodes with the specified label and properties, it creates one, as shown in the following screenshot. OnCreate and OnMatch Whenever, we execute a merge query, a node is either matched or created. Using on create and on match, you can set properties for indicating whether the node is created or matched. Syntax Following is the syntax of OnCreate and OnMatch clauses. MERGE (node:label {properties . . . . . . . . . . .}) ON CREATE SET property.isCreated =”true” ON MATCH SET property.isFound =”true” Example Following is a sample Cypher Query which demonstrates the usage of OnCreate and OnMatch clauses in Neo4j. If the specified node already exists in the database, then the node will be matched and the property with key-value pair isFound = “true” will be created in the node. If the specified node doesn’t exist in the database, then the node will be created, and within it a property with a key-value pair isCreated =”true” will be created. MERGE (Jadeja:player {name: “Ravindra Jadeja”, YOB: 1988, POB: “NavagamGhed”}) ON CREATE SET Jadeja.isCreated = “true” ON MATCH SET Jadeja.isFound = “true” RETURN Jadeja 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. As discussed, since there is

Neo4j – Limit Clause ”; Previous Next The limit clause is used to limit the number of rows in the output. Syntax Following is the syntax of the LIMIT clause. MATCH (n) RETURN n ORDER BY n.name LIMIT 3 Example Before proceeding with the example, create 5 nodes in the Neo4j database as shown below. CREATE(Dhawan:player{name:”shikar Dhawan”, YOB: 1985, runs:363, country: “India”}) CREATE(Jonathan:player{name:”Jonathan Trott”, YOB:1981, runs:229, country:”South Africa”}) CREATE(Sangakkara:player{name:”Kumar Sangakkara”, YOB:1977, runs:222, country:”Srilanka”}) CREATE(Rohit:player{name:”Rohit Sharma”, YOB: 1987, runs:177, country:”India”}) CREATE(Virat:player{name:”Virat Kohli”, YOB: 1988, runs:176, country:”India”}) Following is a sample Cypher Query which returns the nodes created above in a descending order and limits the records in the result to 3. MATCH (n) RETURN n.name, n.runs ORDER BY n.runs DESC LIMIT 3 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. Limit with expression You can also use the LIMIT clause with expression. Example Following is a sample Cypher Query which limits the records using an expression. MATCH (n) RETURN n.name, n.runs ORDER BY n.runs DESC LIMIT toInt(3 * rand())+ 1 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. Print Page Previous Next Advertisements ”;

Neo4j – Where Clause ”; Previous Next Like SQL, Neo4j CQL has provided WHERE clause in CQL MATCH command to filter the results of a MATCH Query. Syntax Following is the syntax of the WHERE clause. MATCH (label) WHERE label.country = “property” RETURN label Example Before proceeding with the example, create five nodes in the database as shown below. CREATE(Dhawan:player{name:”shikar Dhawan”, YOB: 1985, runs:363, country: “India”} CREATE(Jonathan:player{name:”Jonathan Trott”, YOB:1981, runs:229, country:”South Africa”} CREATE(Sangakkara:player{name:”Kumar Sangakkara”, YOB:1977, runs:222, country:”Srilanka”}) CREATE(Rohit:player{name:”Rohit Sharma”, YOB: 1987, runs:177, country:”India”}) CREATE(Virat:player{name:”Virat Kohli”, YOB: 1988, runs:176, country:”India”}) CREATE(Ind:Country {name: “India”, result: “Winners”}) Following is a sample Cypher Query which returns all the players (nodes) that belongs to the country India using WHERE clause. MATCH (player) WHERE player.country = “India” RETURN 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. WHERE Clause with Multiple Conditions You can also use the WHERE clause to verify multiple conditions. Syntax Following is the syntax to use WHERE clause in Neo4j with multiple conditions. MATCH (emp:Employee) WHERE emp.name = ”Abc” AND emp.name = ”Xyz” RETURN emp Example Following is a sample Cypher Query which filters the nodes in the Neo4j database using two conditions. MATCH (player) WHERE player.country = “India” AND player.runs >=175 RETURN 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. Using Relationship with Where Clause You can also use Where clause to filter the nodes using the relationships. Example Assume we have the following graph in the database. Following is a sample Cypher Query to retrieve the top scorer of India using WHERE clause as shown below. MATCH (n) WHERE (n)-[: TOP_SCORER_OF]->( {name: “India”, result: “Winners”}) RETURN n 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. Here you can observe that Neo4j returned the node, which has the relation TOP_SCORER_OF to the country with the node having the name India. Print Page Previous Next Advertisements ”;

Neo4j – Match Clause ”; Previous Next In this chapter, we will learn about Match Clause and all the functions that can be performed using this clause. Get All Nodes Using Match Using the MATCH clause of Neo4j you can retrieve all nodes in the Neo4j database. Example Before proceeding with the example, create 3 nodes and 2 relationships as shown below. CREATE (Dhoni:player {name: “MahendraSingh Dhoni”, YOB: 1981, POB: “Ranchi”}) CREATE (Ind:Country {name: “India”, result: “Winners”}) CREATE (CT2013:Tornament {name: “ICC Champions Trophy 2013”}) CREATE (Ind)-[r1:WINNERS_OF {NRR:0.938 ,pts:6}]->(CT2013) CREATE(Dhoni)-[r2:CAPTAIN_OF]->(Ind) CREATE (Dhawan:player{name: “shikar Dhawan”, YOB: 1995, POB: “Delhi”}) CREATE (Jadeja:player {name: “Ravindra Jadeja”, YOB: 1988, POB: “NavagamGhed”}) CREATE (Dhawan)-[:TOP_SCORER_OF {Runs:363}]->(Ind) CREATE (Jadeja)-[:HIGHEST_WICKET_TAKER_OF {Wickets:12}]->(Ind) Following is the query which returns all the nodes in Neo4j database. MATCH (n) RETURN n 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. Getting All Nodes Under a Specific Label Using match clause, you can get all the nodes under a specific label. Syntax Following is the syntax to get all the nodes under a specific label. MATCH (node:label) RETURN node Example Following is a sample Cypher Query, which returns all the nodes in the database under the label player. MATCH (n:player) RETURN n 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. Match by Relationship You can retrieve nodes based on relationship using the MATCH clause. Syntax Following is the syntax of retrieving nodes based on the relationship using the MATCH clause. MATCH (node:label)<-[: Relationship]-(n) RETURN n Example Following is a sample Cypher Query to retrieve nodes based on relationship using the MATCH clause. MATCH (Ind:Country {name: “India”, result: “Winners”})<-[: TOP_SCORER_OF]-(n) RETURN n.name 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. Delete All Nodes You can delete all the nodes using the MATCH clause. Query Following is the query to delete all the nodes in Neo4j. MATCH (n) detach delete n 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. Print Page Previous Next Advertisements ”;

Neo4j – Overview ”; Previous Next Neo4j is the world”s leading open source Graph Database which is developed using Java technology. It is highly scalable and schema free (NoSQL). What is a Graph Database? A graph is a pictorial representation of a set of objects where some pairs of objects are connected by links. It is composed of two elements – nodes (vertices) and relationships (edges). Graph database is a database used to model the data in the form of graph. In here, the nodes of a graph depict the entities while the relationships depict the association of these nodes. Popular Graph Databases Neo4j is a popular Graph Database. Other Graph Databases are Oracle NoSQL Database, OrientDB, HypherGraphDB, GraphBase, InfiniteGraph, and AllegroGraph. Why Graph Databases? Nowadays, most of the data exists in the form of the relationship between different objects and more often, the relationship between the data is more valuable than the data itself. Relational databases store highly structured data which have several records storing the same type of data so they can be used to store structured data and, they do not store the relationships between the data. Unlike other databases, graph databases store relationships and connections as first-class entities. The data model for graph databases is simpler compared to other databases and, they can be used with OLTP systems. They provide features like transactional integrity and operational availability. RDBMS Vs Graph Database Following is the table which compares Relational databases and Graph databases. Sr.No RDBMS Graph Database 1 Tables Graphs 2 Rows Nodes 3 Columns and Data Properties and its values 4 Constraints Relationships 5 Joins Traversal Advantages of Neo4j Following are the advantages of Neo4j. Flexible data model − Neo4j provides a flexible simple and yet powerful data model, which can be easily changed according to the applications and industries. Real-time insights − Neo4j provides results based on real-time data. High availability − Neo4j is highly available for large enterprise real-time applications with transactional guarantees. Connected and semi structures data − Using Neo4j, you can easily represent connected and semi-structured data. Easy retrieval − Using Neo4j, you can not only represent but also easily retrieve (traverse/navigate) connected data faster when compared to other databases. Cypher query language − Neo4j provides a declarative query language to represent the graph visually, using an ascii-art syntax. The commands of this language are in human readable format and very easy to learn. No joins − Using Neo4j, it does NOT require complex joins to retrieve connected/related data as it is very easy to retrieve its adjacent node or relationship details without joins or indexes. Features of Neo4j Following are the notable features of Neo4j − Data model (flexible schema) − Neo4j follows a data model named native property graph model. Here, the graph contains nodes (entities) and these nodes are connected with each other (depicted by relationships). Nodes and relationships store data in key-value pairs known as properties. In Neo4j, there is no need to follow a fixed schema. You can add or remove properties as per requirement. It also provides schema constraints. ACID properties − Neo4j supports full ACID (Atomicity, Consistency, Isolation, and Durability) rules. Scalability and reliability − You can scale the database by increasing the number of reads/writes, and the volume without effecting the query processing speed and data integrity. Neo4j also provides support for replication for data safety and reliability. Cypher Query Language − Neo4j provides a powerful declarative query language known as Cypher. It uses ASCII-art for depicting graphs. Cypher is easy to learn and can be used to create and retrieve relations between data without using the complex queries like Joins. Built-in web application − Neo4j provides a built-in Neo4j Browser web application. Using this, you can create and query your graph data. Drivers − Neo4j can work with − REST API to work with programming languages such as Java, Spring, Scala etc. Java Script to work with UI MVC frameworks such as Node JS. It supports two kinds of Java API: Cypher API and Native Java API to develop Java applications. In addition to these, you can also work with other databases such as MongoDB, Cassandra, etc. Indexing − Neo4j supports Indexes by using Apache Lucence. Print Page Previous Next Advertisements ”;

Neo4j – Set Clause ”; Previous Next Using Set clause, you can add new properties to an existing Node or Relationship, and also add or update existing Properties values. In this chapter, we are going to discuss how to − Set a property Remove a property Set multiple properties Set a label on a node Set multiple labels on a node Setting a Property Using the SET clause, you can create a new property in a node. Syntax Following is the syntax for setting a property. MATCH (node:label{properties . . . . . . . . . . . . . . }) SET node.property = value RETURN node Example Before proceeding with the example, first create a node named Dhawan as shown below. CREATE (Dhawan:player{name: “shikar Dhawan”, YOB: 1985, POB: “Delhi”}) Following is a sample Cypher Query to create a property named “highestscore” with value “187”. MATCH (Dhawan:player{name: “shikar Dhawan”, YOB: 1985, POB: “Delhi”}) SET Dhawan.highestscore = 187 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 screnshot. 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 a property with a key-value pair highestscore/187 is created in the node named “Dhawan”. Removing a Property You can remove an existing property by passing NULL as value to it. Syntax Following is the syntax of removing a property from a node using the SET clause. MATCH (node:label {properties}) SET node.property = NULL RETURN node Example Before proceeding with the example, first create a node “jadeja” as shown below. Create (Jadeja:player {name: “Ravindra Jadeja”, YOB: 1988, POB: “NavagamGhed”}) Following is a sample Cypher Query which removes the property named POB from this node using the SET clause as shown below. MATCH (Jadeja:player {name: “Ravindra Jadeja”, YOB: 1988, POB: “NavagamGhed”}) SET Jadeja.POB = NULL RETURN Jadeja 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. Here you can observe that the variable named POB was deleted. Setting Multiple Properties In the same way, you can create multiple properties in a node using the Set clause. To do so, you need to specify these key value pairs with commas. Syntax Following is the syntax to create multiple properties in a node using the SET clause. MATCH (node:label {properties}) SET node.property1 = value, node.property2 = value RETURN node Example Following is a sample Cypher Query which creates multiple properties in a node using the SET clause in Neo4j. MATCH (Jadeja:player {name: “Ravindra Jadeja”, YOB: 1988}) SET Jadeja.POB: “NavagamGhed”, Jadeja.HS = “90” RETURN Jadeja 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. Here you can observe that properties named POB and HS were created. Setting a Label on a Node You can set a label to an existing node using the SET clause. Syntax Following is the syntax to set a label to an existing node. MATCH (n {properties . . . . . . . }) SET n :label RETURN n Example Before proceeding with the example, first create a node “Anderson” as shown below. CREATE (Anderson {name: “James Anderson”, YOB: 1982, POB: “Burnely”}) Following is a sample Cypher Query to set a label on a node using the SET clause. This query adds the label “player” to the node Anderson and returns it. MATCH (Anderson {name: “James Anderson”, YOB: 1982, POB: “Burnely”}) SET Anderson: player RETURN Anderson 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. Here you can observe that the label named “player” is added to the node. Setting Multiple Labels on a Node You can set multiple labels to an existing node using the SET clause. Here you need to specify the labels by separating them with colons “:”. Syntax Following is the syntax to set multiple labels to an existing node using the SET clause. MATCH (n {properties . . . . . . . }) SET n :label1:label2 RETURN n Example Before proceeding with the example, first create a node named “Ishant” as shown below. CREATE (Ishant {name: “Ishant Sharma”, YOB: 1988, POB: “Delhi”}) Following is a sample Cypher Query used to create multiple labels on a node using the SET clause. MATCH (Ishant {name: “Ishant Sharma”, YOB: 1988, POB: “Delhi”}) SET Ishant: player:person RETURN Ishant 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

Neo4j CQL – Creating a Relationship ”; Previous Next In Noe4j, a relationship is an element using which we connect two nodes of a graph. These relationships have direction, type, and the form patterns of data. This chapter teaches you how to − Create relationships Create a relationship between the existing nodes Create a relationship with label and properties Creating Relationships We can create a relationship using the CREATE clause. We will specify relationship within the square braces “[ ]” depending on the direction of the relationship it is placed between hyphen “ – ” and arrow “ → ” as shown in the following syntax. Syntax Following is the syntax to create a relationship using the CREATE clause. CREATE (node1)-[:RelationshipType]->(node2) Example First of all, create two nodes Ind and Dhawan in the database, as shown below. CREATE (Dhawan:player{name: “Shikar Dhawan”, YOB: 1985, POB: “Delhi”}) CREATE (Ind:Country {name: “India”}) Now, create a relationship named BATSMAN_OF between these two nodes as − CREATE (Dhawan)-[r:BATSMAN_OF]->(Ind) Finally, return both the nodes to see the created relationship. RETURN Dhawan, Ind 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. Creating a Relationship Between the Existing Nodes You can also create a relationship between the existing nodes using the MATCH clause. Syntax Following is the syntax to create a relationship using the MATCH clause. MATCH (a:LabeofNode1), (b:LabeofNode2) WHERE a.name = “nameofnode1″ AND b.name = ” nameofnode2″ CREATE (a)-[: Relation]->(b) RETURN a,b Example Following is a sample Cypher Query which creates a relationship using the match clause. MATCH (a:player), (b:Country) WHERE a.name = “Shikar Dhawan” AND b.name = “India” CREATE (a)-[r: BATSMAN_OF]->(b) RETURN a,b 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. Creating a Relationship with Label and Properties You can create a relationship with label and properties using the CREATE clause. Syntax Following is the syntax to create a relationship with label and properties using the CREATE clause. CREATE (node1)-[label:Rel_Type {key1:value1, key2:value2, . . . n}]-> (node2) Example Following is a sample Cypher Query which creates a relationship with label and properties. MATCH (a:player), (b:Country) WHERE a.name = “Shikar Dhawan” AND b.name = “India” CREATE (a)-[r:BATSMAN_OF {Matches:5, Avg:90.75}]->(b) RETURN a,b 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. Creating a Complete Path In Neo4j, a path is formed using continuous relationships. A path can be created using the create clause. Syntax Following is the syntax to create a path in Neo4j using the CREATE clause. CREATE p = (Node1 {properties})-[:Relationship_Type]-> (Node2 {properties})[:Relationship_Type]->(Node3 {properties}) RETURN p Example 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. Print Page Previous Next Advertisements ”;

Neo4j – Building Blocks ”; Previous Next Neo4j Graph Database has the following building blocks − Nodes Properties Relationships Labels Data Browser Node Node is a fundamental unit of a Graph. It contains properties with key-value pairs as shown in the following image. Here, Node Name = “Employee” and it contains a set of properties as key-value pairs. Properties Property is a key-value pair to describe Graph Nodes and Relationships. Key = Value Where Key is a String and Value may be represented using any Neo4j Data types. Relationships Relationships are another major building block of a Graph Database. It connects two nodes as depicted in the following figure. Here, Emp and Dept are two different nodes. “WORKS_FOR” is a relationship between Emp and Dept nodes. As it denotes, the arrow mark from Emp to Dept, this relationship describes − Emp WORKS_FOR Dept Each relationship contains one start node and one end node. Here, “Emp” is a start node, and “Dept” is an end node. As this relationship arrow mark represents a relationship from “Emp” node to “Dept” node, this relationship is known as an “Incoming Relationship” to “Dept” Node and “Outgoing Relationship” to “Emp” node. Like nodes, relationships also can contain properties as key-value pairs. Here, “WORKS_FOR” relationship has one property as key-value pair. Id = 123 It represents an Id of this relationship. Labels Label associates a common name to a set of nodes or relationships. A node or relationship can contain one or more labels. We can create new labels to existing nodes or relationships. We can remove the existing labels from the existing nodes or relationships. From the previous diagram, we can observe that there are two nodes. Left side node has a Label: “Emp” and the right side node has a Label: “Dept”. Relationship between those two nodes also has a Label: “WORKS_FOR”. Note − Neo4j stores data in Properties of Nodes or Relationships. Neo4j Data Browser Once we install Neo4j, we can access Neo4j Data Browser using the following URL http://localhost:7474/browser/ Neo4j Data Browser is used to execute CQL commands and view the output. Here, we need to execute all CQL commands at dollar prompt: “$” Type commands after the dollar symbol and click the “Execute” button to run your commands. It interacts with Neo4j Database Server, retrieves and displays the results just below the dollar prompt. Use “VI View” button to view the results in diagrams format. The above diagram shows results in “UI View” format. Use “Grid View” button to view the results in Grid View. The following diagram shows the same results in “Grid View” format. When we use “Grid View” to view our Query results, we can export them into a file in two different formats. CSV Click the “Export CSV” button to export the results in csv file format. JSON Click the “Export JSON” button to export the results in JSON file format. However, if we use “UI View” to see our Query results, we can export them into a file in only one format: JSON Print Page Previous Next Advertisements ”;

Neo4j Tutorial PDF Version Quick Guide Resources Job Search Discussion Neo4j is one of the popular Graph Databases and Cypher Query Language (CQL). Neo4j is written in Java Language. This tutorial explains the basics of Neo4j, Java with Neo4j, and Spring DATA with Neo4j. The tutorial is divided into sections such as Neo4j Introduction, Neo4j CQL, Neo4j CQL Functions, Neo4j Admin, etc. Each of these sections contain related topics with simple and useful examples. Audience This tutorial has been prepared for beginners to help them understand the basic to advanced concepts of Neo4j. It will give you enough understanding on Neo4j from where you can take yourself to a higher level of expertise. Prerequisites Before proceeding with this tutorial, you should have basic knowledge of Database, Graph Theory, Java, and Spring Framework. Print Page Previous Next Advertisements ”;

Neo4j – Data Model ”; Previous Next Neo4j Property Graph Data Model Neo4j Graph Database follows the Property Graph Model to store and manage its data. Following are the key features of Property Graph Model − The model represents data in Nodes, Relationships and Properties Properties are key-value pairs Nodes are represented using circle and Relationships are represented using arrow keys Relationships have directions: Unidirectional and Bidirectional Each Relationship contains “Start Node” or “From Node” and “To Node” or “End Node” Both Nodes and Relationships contain properties Relationships connects nodes In Property Graph Data Model, relationships should be directional. If we try to create relationships without direction, then it will throw an error message. In Neo4j too, relationships should be directional. If we try to create relationships without direction, then Neo4j will throw an error message saying that “Relationships should be directional”. Neo4j Graph Database stores all of its data in Nodes and Relationships. We neither need any additional RRBMS Database nor any SQL database to store Neo4j database data. It stores its data in terms of Graphs in its native format. Neo4j uses Native GPE (Graph Processing Engine) to work with its Native graph storage format. The main building blocks of Graph DB Data Model are − Nodes Relationships Properties Following is a simple example of a Property Graph. Here, we have represented Nodes using Circles. Relationships are represented using Arrows. Relationships are directional. We can represent Node”s data in terms of Properties (key-value pairs). In this example, we have represented each Node”s Id property within the Node”s Circle. Print Page Previous Next Advertisements ”;