Cypher : Cypher Query Language what is a cypher?

These developer guides and tutorials show you how to construct queries in Cypher to store and retrieve data from Neo4j. There are a variety of ways to learn Cypher. Feel free to check out our other Cypher learning tools, as well!

The first two guides will explain the basic concepts of Cypher query syntax, including how to create and query data. Cypher is based on ASCII art, so the syntax is easily understood and makes queries more self-explanatory. It focuses on the clarity of expressing what to retrieve from a graph, not on how to retrieve it.

We will discuss the keywords for each CRUD operation and how to specify nodes, relationships, and properties in the query language. Learning how to specify patterns and filter data results will allow you to traverse the graph or add and remove data.

Cypher Basics I
Cypher Basics II

Most types of queries are not simple data entry or retrieval. Often, you will need to write queries that retrieve sets of data that fall within certain criteria. This is where the capability to filter query results becomes very valuable.

Being able to trim out results that are unwanted and only retrieve certain data is important for application functionality and user experience, but also increases update and read performance because it is only returning results that the user cares about.

In this guide, we will walk through many of the ways you can limit your query results to what you need and control how they are returned to output. Much of the syntax and functionality for these clauses is similar to SQL and will probably be familiar to most developers with data querying experience.

Filtering Cypher Query Results

Just as in most programming languages, some utility capabilities are needed to perform basic functions on data being retrieved from a database. Functionality such as counting results, grouping data by values, and finding minimum/maximum values are often bundled into the language itself to provide those capabilities in a standard, out-of-the-box way to all developers.

Cypher also includes these functions to perform mathematical, aggregation, and other utility operations needed within queries. This guide will show you what is possible within Cypher and show you how to structure the syntax.

Cypher Functions and Aggregations

With the release of Neo4j 3.4, Cypher added support for native data types in the database. Working with dates, datetimes, timezones, and durations is a necessary part of data and databases.

From converting certain values to dates, creating instants, or calculating durations, this guide will cover the basics of using Cypher for Neo4j native data types.

Cypher Dates

Many query languages include the capability to run subqueries inside outer queries, and Cypher offers this, as well. There are a couple of different approaches to syntax, depending on the type of subquery needed.

We can use existential subqueries to filter more complex scenarios like patterns and even entire nested queries for more accurate and focused results. We can also use result-returning subqueries to sort and order filtered results. While organizing filtered results was previously possible in Cypher, providing subquery support allows us to simplify the syntax and avoid using APOC procedures or additional Cypher clauses to pass and sort values along the way.

Some syntax in Cypher requires a specific style or casing, while another Cipher syntax is not particular in styling. In either case, we have compiled some of the recommended and required styling for writing Cipher queries. This guide will walk through various components of typical syntax to help you write logical and readable Cipher queries.

Cipher was based upon the power and capabilities of SQL – the standard for querying relational databases. However, Cipher was designed and optimized specifically for graph data and traversals. While neither language is better or worse, they each have their strengths and purposes.

SQL developers will see certain keywords and constructs that are the same or very similar to their existing knowledge in the predecessor language. This guide was written with SQL developers in mind to bridge the gap and bring existing knowledge across to learning Cipher. Through examples of both languages, you will see the logical structures and syntax of each and how each was designed for its purpose.

Cypher provides powerful capabilities out of the box. However, developers may need or want additional functionality for business cases or special scenarios. Extending Cipher in Neo4j is simple with user-defined procedures and functions.

User-defined procedures and functions can be written for a variety of cases and simple or complex operations. This guide will show you how to create custom add-ons and how to compile them so that the database recognizes them as part of Cipher.

Before we get too carried away with creating all of our functionality customs, though, we will also talk about how certain libraries and functionality have already been developed to work seamlessly with Neo4j. Learn where you can look to find out if code already exists for your capability or if you need to write your own custom functionality!

User-Defined Procedures and Functions
APOC: Neo4j’s Standard Utility Library

With Cipher structure and syntax learned so far, you can dive into building your own recommendation engine to use graph data and Cipher to recommend movies, colleagues, cuisines, and more.

This guide will walk through using queries and filtering that take advantage of the relationships in a graph in order to lend insight into habits and hidden connections and provide valuable recommendations.