Neo4j WHERE, FILTERS, and Parameters

1. WHERE Clause

The WHERE clause in Cypher is used to filter the results of a query. It allows you to specify conditions that nodes or relationships must meet to be included in the results.

Example:

MATCH (n:Person)
WHERE n.age > 30 AND n.city = 'New York'
RETURN n
        

2. Filters

Filters in Cypher are expressions used to refine the results of a query. They can be applied within the WHERE clause or used in other contexts.

Common Filters:

• EXISTS() - Checks if a property exists.
• STARTS WITH - Checks if a string starts with a given substring.
• IN - Checks if a value exists in a list.

Example:

MATCH (n:Movie)
WHERE n.title STARTS WITH 'The' AND n.genre IN ['Action', 'Adventure']
RETURN n
        

3. Parameters

Parameters in Cypher queries allow you to substitute values dynamically. This is useful for executing queries with different values without altering the query structure.

Setting Parameters:

• Use WITH clause to pass parameters.
• Utilize $parameterName syntax in the query.

Example:

WITH {nameParam} AS name
MATCH (n:Person)
WHERE n.name = name
RETURN n
        

4. Best Practices

When using WHERE clauses, filters, and parameters, consider the following best practices:

• Use parameters instead of hardcoding values to enhance security and performance.
• Combine conditions logically to avoid overly complex queries.
• Utilize indexes on properties used in the WHERE clause to speed up queries.

5. FAQ