NEO4J CQL - UNION. Like SQL, Neo4j CQL has two clauses to combine two different results into one set of results

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Randolf Hampton
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1 NEO4J CQL - Copyright tutorialspoint.com Like SQL, Neo4j CQL has two clauses to combine two different results into one set of results ALL Clause It combines and returns common rows from two set of results into a single set of results. It does not return duplicate rows from two nodes. Restriction: Result column types and names from two set of results have to match that means column names should be same and column's data types should be same. Clause syntax <MATCH Command1> <MATCH Command2> Syntax Description S.No. Syntax Element Description 1. <MATCH Command1> It is CQL MATCH command one to be used by clause. 2. <MATCH Command2> It is CQL MATCH command two to be used by clause. 3. It is a Neo4j CQL keyword for clause. Note - If both queries does not return same column names and data types, then it throws an error. In this chapter, we will take a Banking application nodes : CreditCard and DebitCard to explain clause CreditCard Node data

with examples Example This Example demonstrates what will happen if both queries of clause does have same names or same data types to their

2 Step 2 - Type the below command at dollar prompt in Data Browser. MATCH (cc:creditcard) RETURN cc DebitCard Node data Step 2 - Type the below command at dollar prompt in Data Browser. MATCH (dc:debitcard) RETURN dc We will use this data to explain the usage of Neo4j CQL with examples Example This Example demonstrates what will happen if both queries of clause does have same names or same data types to their columns. Step 2 - Type the below command at dollar prompt in Data Browser. MATCH (cc:creditcard) RETURN cc.id,cc.number MATCH (dc:debitcard) RETURN dc.id,dc.number

Step 3 - Click on Execute button and see the success message in the Data Browser. It shows that both queries should have same column names. First query has : cc.id,cc.number. Second query has : dc.

3 Step 3 - Click on Execute button and see the success message in the Data Browser. It shows that both queries should have same column names. First query has : cc.id,cc.number. Second query has : dc.id,dc.number. Here both CreditCard and DebitCard has same property names : id and number, but they have prefixed with different node names. That's why command is showing this error message. To avoid this error, Neo4j CQL has provided "AS" clause. Like CQL, Neo4j CQL "AS" clause is used to give some alias name. Example This Example demonstrates How to use clause to retrieve data from two nodes. Step 1 - Type the below command at dollar prompt in Data Browser and Click on Execute button. MATCH (cc:creditcard) RETURN cc.id as id,cc.number as number,cc.name as name, cc.valid_from as valid_from,cc.valid_to as valid_to MATCH (dc:debitcard) RETURN dc.id as id,dc.number as number,dc.name as name, dc.valid_from as valid_from,dc.valid_to as valid_to

4 Here we can observe this command returns 9 rows without duplicate rows because clause filters them. ALL Clause It combines and returns all rows from two set of results into a single set of results. It returns duplicate rows also from two nodes. Restriction Result column types and names from two set of results have to match that means column names should be same and column's data types should be same. ALL Clause syntax <MATCH Command1> ALL <MATCH Command2> Syntax Description S.No. Syntax Element Description 1. <MATCH Command1> It is CQL MATCH command one to be used by clause. 2. <MATCH Command2> It is CQL MATCH command two to be used by clause. 3. ALL It is a Neo4j CQL keyword for ALL clause. Note - If both queries does not return same column names and data types, then it throws an error. In this chapter, we will take a Banking application nodes : CreditCard and DebitCard to explain clause CreditCard Node data Step 1 - Type the below command at dollar prompt in Data Browser.

5 MATCH (cc:creditcard) RETURN cc DebitCard Node data Step 1 - Type the below command at dollar prompt in Data Browser. MATCH (dc:debitcard) RETURN dc We will use this data to explain the usage of Neo4j CQL with examples Example This Example demonstrates what will happen if both queries of clause does have same names or same data types to their columns.

It is Neo4j Data Browser Homepage Step 2 - Type the below command at dollar prompt in Data Browser. MATCH (cc:creditcard) RETURN cc.id as id,cc.number as number,cc.name as name, cc.

6 It is Neo4j Data Browser Homepage Step 2 - Type the below command at dollar prompt in Data Browser. MATCH (cc:creditcard) RETURN cc.id as id,cc.number as number,cc.name as name, cc.valid_from as valid_from,cc.valid_to as valid_to ALL MATCH (dc:debitcard) RETURN dc.id as id,dc.number as number,dc.name as name, dc.valid_from as valid_from,dc.valid_to as valid_to Step 1 - Click on Execute button and see the success message in the Data Browser. Here we can observe this command returns 10 rows with duplicate rows because ALL clause does not filter them. If we use clause, it returns only 9 rows. Please refer clause chapter to check this.

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