build-a-c++-app-with-cockroachdb.md

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Build a C++ App with CockroachDB	Learn how to use CockroachDB from a simple C++ application with a low-level client driver.	false	false

This tutorial shows you how build a simple C++ application with CockroachDB using a PostgreSQL-compatible driver.

We have tested the C++ libpqxx driver enough to claim beta-level support, so that driver is featured here. If you encounter problems, please open an issue with details to help us make progress toward full support.

Before You Begin

Make sure you have already installed CockroachDB.

Step 1. Install the libpqxx driver

Install the C++ libpqxx driver as described in the official documentation.

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

Step 5. Run the C++ 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.

Download the basic-sample.cpp file, or create the file yourself and copy the code into it.

{% include copy-clipboard.html %}

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

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.

{{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}}

Download the txn-sample.cpp file, or create the file yourself and copy the code into it.

{% include copy-clipboard.html %}

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

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

{% include copy-clipboard.html %}

$ 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 C++ libpqxx driver.

{% include app/see-also-links.md %}