build-a-nodejs-app-with-cockroachdb.md

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Build a Node.js App with CockroachDB	Learn how to use CockroachDB from a simple Node.js application with the Node.js pg driver.	false	true

Use pg Use Sequelize

This tutorial shows you how build a simple Node.js application with CockroachDB using a PostgreSQL-compatible driver or ORM. We've tested and can recommend the Node.js pg driver and the Sequelize ORM, so those are featured here.

Before You Begin

Make sure you have already installed CockroachDB.

Step 1. Install Node.js packages

To let your application communicate with CockroachDB, install the Node.js pg driver:

$ npm install pg

The example app on this page also requires async:

$ npm install async

{% include app/common-steps.md %}

Step 5. Run the Node.js code

Now that you have a database and a user, you'll run code to create a table and insert some rows, and then you'll run code to read and update values as an atomic transaction.

Basic Statements

First, use the following code to connect as the maxroach user and execute some basic SQL statements, creating a table, inserting rows, and reading and printing the rows.

You can copy the code or download it directly.

{% include app/basic-sample.js %}

Transaction (with retry logic)

Next, use the following code to again connect as the maxroach user but this time execute a batch of statements as an atomic transaction to transfer funds from one account to another, where all included statements are either committed or aborted.

You can copy the code or download it directly.

{{site.data.alerts.callout_info}}With the default SERIALIZABLE isolation level, CockroachDB may require the client to retry a transaction in case of read/write contention. CockroachDB provides a generic retry function that runs inside a transaction and retries it as needed. You can copy and paste the retry function from here into your code.{{site.data.alerts.end}}

{% include app/txn-sample.js %}

After running the code, use the built-in SQL client to verify that funds were transferred from one account to another:

$ cockroach sql --insecure -e 'SELECT id, balance FROM accounts' --database=bank

+----+---------+
| id | balance |
+----+---------+
|  1 |     900 |
|  2 |     350 |
+----+---------+
(2 rows)

What's Next?

Read more about using the Node.js pg driver.

You might also be interested in using a local cluster to explore the following core CockroachDB features:

• Data Replication
• Fault Tolerance & Recovery
• Automatic Rebalancing