Build a Simple CRUD Go App with CockroachDB and the Go pgx Driver

This tutorial shows you how build a simple CRUD Go application with CockroachDB and the Go pgx driver.

Step 1. Start CockroachDB

Use CockroachDB Cloud

Choose your installation method

You can create a CockroachDB Basic cluster using either the CockroachDB Cloud Console, a web-based graphical user interface (GUI) tool, or ccloud, a command-line interface (CLI) tool.

Cloud Console (GUI)

Create a free cluster

Organizations without billing information on file can only create one CockroachDB Basic cluster.

1. If you haven’t already, sign up for a CockroachDB Cloud account.

2. Log in to your CockroachDB Cloud account.

3. On the Clusters page, click Create cluster.

4. On the Select a plan page, select Basic.

5. On the Cloud & Regions page, select a cloud provider (GCP or AWS) in the Cloud provider section.

6. In the Regions section, select a region for the cluster. Refer to for the regions where CockroachDB Basic clusters can be deployed. To create a multi-region cluster, click Add region and select additional regions.

7. Click Next: Capacity.

8. On the Capacity page, select Start for free. Click Next: Finalize.

9. On the Finalize page, click Create cluster.

   Your cluster will be created in a few seconds and the Create SQL user dialog will display.

Create a SQL user

The Create SQL user dialog allows you to create a new SQL user and password.

1. Enter a username in the SQL user field or use the one provided by default.

2. Click Generate & save password.

3. Copy the generated password and save it in a secure location.

4. Click Next.

   Currently, all new SQL users are created with admin privileges. For more information and to change the default settings, see .

Get the connection string

The Connect to cluster dialog shows information about how to connect to your cluster.

1. Select General connection string from the Select option dropdown.

2. Open the General connection string section, then copy the connection string provided and save it in a secure location.

   The sample application used in this tutorial uses system CA certificates for server certificate verification, so you can skip the Download CA Cert instructions.

The connection string is pre-populated with your username, password, cluster name, and other details. Your password, in particular, will be provided only once. Save it in a secure place (Cockroach Labs recommends a password manager) to connect to your cluster in the future. If you forget your password, you can reset it by going to the SQL Users page for the cluster, found at https://cockroachlabs.cloud/cluster/<CLUSTER ID>/users.

ccloud CLI

Follow these steps to create a CockroachDB Basic cluster using the ccloud CLI tool.

The ccloud CLI tool is in Preview.

Install ccloud

Mac

You can install ccloud using either Homebrew or by downloading the binary.

Use Homebrew

1. Install Homebrew.

2. Install using the ccloud tap:

   brew install cockroachdb/tap/ccloud
   

Download the binary

In a terminal, enter the following command to download and extract the ccloud binary and add it to your PATH:

curl https://binaries.cockroachdb.com/ccloud/ccloud_darwin-amd64_.tar.gz | tar -xJ && cp -i ccloud /usr/local/bin/

Use the ARM 64 binary if you have an M-series Mac:

curl https://binaries.cockroachdb.com/ccloud/ccloud_darwin-arm64_.tar.gz | tar -xJ && cp -i ccloud /usr/local/bin/

Linux

In a terminal, enter the following command to download and extract the ccloud binary and add it to your PATH:

curl https://binaries.cockroachdb.com/ccloud/ccloud_linux-amd64_.tar.gz | tar -xz && cp -i ccloud /usr/local/bin/

Windows

In a PowerShell window, enter the following command to download and extract the ccloud binary and add it to your PATH:

$ErrorActionPreference = "Stop"; [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; $ProgressPreference = 'SilentlyContinue'; $null = New-Item -Type Directory -Force $env:appdata/ccloud; Invoke-WebRequest -Uri https://binaries.cockroachdb.com/ccloud/ccloud_windows-amd64_.zip -OutFile ccloud.zip; Expand-Archive -Force -Path ccloud.zip; Copy-Item -Force ccloud/ccloud.exe -Destination $env:appdata/ccloud; $Env:PATH += ";$env:appdata/ccloud"; # We recommend adding ";$env:appdata/ccloud" to the Path variable for your system environment. See https://docs.microsoft.com/powershell/module/microsoft.powershell.core/about/about_environment_variables#saving-changes-to-environment-variables for more information.

Run ccloud quickstart to create a new cluster, create a SQL user, and retrieve the connection string.

The easiest way of getting started with CockroachDB Cloud is to use ccloud quickstart. The ccloud quickstart command guides you through logging in to CockroachDB Cloud, creating a new CockroachDB Basic cluster, and connecting to the new cluster. Run ccloud quickstart and follow the instructions:

ccloud quickstart

The ccloud quickstart command will open a browser window to log you in to CockroachDB Cloud. If you are new to CockroachDB Cloud, you can register using one of the single sign-on (SSO) options, or create a new account using an email address.

The ccloud quickstart command will prompt you for the cluster name, cloud provider, and cloud provider region, then ask if you want to connect to the cluster. Each prompt has default values that you can select, or change if you want a different option.

Select General connection string, then copy the connection string displayed and save it in a secure location. The connection string is the line starting postgresql://.

? How would you like to connect? General connection string
Retrieving cluster info: succeeded
 Downloading cluster cert to /Users/maxroach/.postgresql/root.crt: succeeded
postgresql://maxroach:[e-mail]:26257/defaultdb?sslmode=verify-full&sslrootcert=%2FUsers%2Fmaxroach%2F.postgresql%2Froot.crt

Use a Local Cluster

1. If you haven’t already, .

2. Run the command:

   $ cockroach start-single-node --advertise-addr 'localhost' --insecure
   

   This starts an insecure, single-node cluster.

3. Take note of the following connection information in the SQL shell welcome text:

   CockroachDB node starting at 2021-08-30 17:25:30.06524 +0000 UTC (took 4.3s)
   build:               CCL v21.1.6 @ 2021/07/20 15:33:43 (go1.15.11)
   webui:               http://localhost:8080
   sql:                 postgresql://root@localhost:26257?sslmode=disable
   

   You’ll use the sql connection string to connect to the cluster later in this tutorial.

The --insecure flag used in this tutorial is intended for non-production testing only. To run CockroachDB in production, use a secure cluster instead.

Step 2. Get the code

Clone the code’s GitHub repo:

$ git clone https://github.com/cockroachlabs/example-app-go-pgx/

The project has the following directory structure:

├── README.md
└── main.go

The main.go file contains the code for CREATE TABLE, INSERT, SELECT, UPDATE, and DELETE SQL operations. The file also executes the main method of the program.

package main

	"context"
	"log"
	"os"

	"github.com/cockroachdb/cockroach-go/v2/crdb/crdbpgxv5"
	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
)

func initTable(ctx context.Context, tx pgx.Tx) error {
	// Dropping existing table if it exists
	log.Println("Drop existing accounts table if necessary.")
	if _, err := tx.Exec(ctx, "DROP TABLE IF EXISTS accounts"); err != nil {
		return err
	}

	// Create the accounts table
	log.Println("Creating accounts table.")
	if _, err := tx.Exec(ctx,
		"CREATE TABLE accounts (id UUID PRIMARY KEY DEFAULT gen_random_uuid(), balance INT8)"); err != nil {
		return err
	}
	return nil
}

func insertRows(ctx context.Context, tx pgx.Tx, accts [4]uuid.UUID) error {
	// Insert four rows into the "accounts" table.
	log.Println("Creating new rows...")
	if _, err := tx.Exec(ctx,
		"INSERT INTO accounts (id, balance) VALUES ($1, $2), ($3, $4), ($5, $6), ($7, $8)", accts[0], 250, accts[1], 100, accts[2], 500, accts[3], 300); err != nil {
		return err
	}
	return nil
}

func printBalances(conn *pgx.Conn) error {
	rows, err := conn.Query(context.Background(), "SELECT id, balance FROM accounts")
	if err != nil {
		log.Fatal(err)
	}
	defer rows.Close()
	for rows.Next() {
		var id uuid.UUID
		var balance int
		if err := rows.Scan(&id, &balance); err != nil {
			log.Fatal(err)
		}
		log.Printf("%s: %d\n", id, balance)
	}
	return nil
}

func transferFunds(ctx context.Context, tx pgx.Tx, from uuid.UUID, to uuid.UUID, amount int) error {
	// Read the balance.
	var fromBalance int
	if err := tx.QueryRow(ctx,
		"SELECT balance FROM accounts WHERE id = $1", from).Scan(&fromBalance); err != nil {
		return err
	}

	if fromBalance < amount {
		log.Println("insufficient funds")
	}

	// Perform the transfer.
	log.Printf("Transferring funds from account with ID %s to account with ID %s...", from, to)
	if _, err := tx.Exec(ctx,
		"UPDATE accounts SET balance = balance - $1 WHERE id = $2", amount, from); err != nil {
		return err
	}
	if _, err := tx.Exec(ctx,
		"UPDATE accounts SET balance = balance + $1 WHERE id = $2", amount, to); err != nil {
		return err
	}
	return nil
}

func deleteRows(ctx context.Context, tx pgx.Tx, one uuid.UUID, two uuid.UUID) error {
	// Delete two rows into the "accounts" table.
	log.Printf("Deleting rows with IDs %s and %s...", one, two)
	if _, err := tx.Exec(ctx,
		"DELETE FROM accounts WHERE id IN ($1, $2)", one, two); err != nil {
		return err
	}
	return nil
}

func main() {
	// Read in connection string
	config, err := pgx.ParseConfig(os.Getenv("DATABASE_URL"))
	if err != nil {
		log.Fatal(err)
	}
	config.RuntimeParams["application_name"] = "$ docs_simplecrud_gopgx"
	conn, err := pgx.ConnectConfig(context.Background(), config)
	if err != nil {
		log.Fatal(err)
	}
	defer conn.Close(context.Background())

	// Set up table
	err = crdbpgx.ExecuteTx(context.Background(), conn, pgx.TxOptions{}, func(tx pgx.Tx) error {
		return initTable(context.Background(), tx)
	})

	// Insert initial rows
	var accounts [4]uuid.UUID
	for i := 0; i < len(accounts); i++ {
		accounts[i] = uuid.New()
	}

	err = crdbpgx.ExecuteTx(context.Background(), conn, pgx.TxOptions{}, func(tx pgx.Tx) error {
		return insertRows(context.Background(), tx, accounts)
	})
	if err == nil {
		log.Println("New rows created.")
	} else {
		log.Fatal("error: ", err)
	}

	// Print out the balances
	log.Println("Initial balances:")
	printBalances(conn)

	// Run a transfer
	err = crdbpgx.ExecuteTx(context.Background(), conn, pgx.TxOptions{}, func(tx pgx.Tx) error {
		return transferFunds(context.Background(), tx, accounts[2], accounts[1], 100)
	})
	if err == nil {
		log.Println("Transfer successful.")
	} else {
		log.Fatal("error: ", err)
	}

	// Print out the balances
	log.Println("Balances after transfer:")
	printBalances(conn)

	// Delete rows
	err = crdbpgx.ExecuteTx(context.Background(), conn, pgx.TxOptions{}, func(tx pgx.Tx) error {
		return deleteRows(context.Background(), tx, accounts[0], accounts[1])
	})
	if err == nil {
		log.Println("Rows deleted.")
	} else {
		log.Fatal("error: ", err)
	}

	// Print out the balances
	log.Println("Balances after deletion:")
	printBalances(conn)
}

CockroachDB may require the in the case of read/write . The CockroachDB Go client includes a generic retry function (ExecuteTx()) that runs inside a transaction and retries it as needed. The code sample shows how you can use this function to wrap SQL statements.

Step 3. Initialize the database

1. Navigate to the example-app-go-pgx directory:

   $ cd example-app-go-pgx
   

2. Set the DATABASE_URL environment variable to the connection string for your cluster:

   export DATABASE_URL="postgresql://root@localhost:26257/defaultdb?sslmode=disable"
   
   export DATABASE_URL="{connection-string}"
   

   Where is the connection string you copied earlier.

Step 4. Run the code

1. Initialize the module:

   $ go mod tidy
   

2. Run the code:

   $ go run main.go
   

   The output should look similar to the following:

   2023/03/24 13:48:13 Drop existing accounts table if necessary.
   2023/03/24 13:48:13 Creating accounts table.
   2023/03/24 13:48:13 Creating new rows...
   2023/03/24 13:48:13 New rows created.
   2023/03/24 13:48:13 Initial balances:
   2023/03/24 13:48:13 19a2b534-11f6-4bbd-ab50-b94c44479280: 500
   2023/03/24 13:48:13 882bb8be-31cb-4481-8e28-69b0566a322b: 300
   2023/03/24 13:48:13 b8cbefed-37ee-4bae-b5b0-3bcfb7a6d3bf: 250
   2023/03/24 13:48:13 d0a238d5-96bd-42d7-89a3-3e2448b3137b: 100
   2023/03/24 13:48:14 Transferring funds from account with ID 19a2b534-11f6-4bbd-ab50-b94c44479280 to account with ID d0a238d5-96bd-42d7-89a3-3e2448b3137b...
   2023/03/24 13:48:14 Transfer successful.
   2023/03/24 13:48:14 Balances after transfer:
   2023/03/24 13:48:14 19a2b534-11f6-4bbd-ab50-b94c44479280: 400
   2023/03/24 13:48:14 882bb8be-31cb-4481-8e28-69b0566a322b: 300
   2023/03/24 13:48:14 b8cbefed-37ee-4bae-b5b0-3bcfb7a6d3bf: 250
   2023/03/24 13:48:14 d0a238d5-96bd-42d7-89a3-3e2448b3137b: 200
   2023/03/24 13:48:14 Deleting rows with IDs b8cbefed-37ee-4bae-b5b0-3bcfb7a6d3bf and d0a238d5-96bd-42d7-89a3-3e2448b3137b...
   2023/03/24 13:48:14 Rows deleted.
   2023/03/24 13:48:14 Balances after deletion:
   2023/03/24 13:48:14 19a2b534-11f6-4bbd-ab50-b94c44479280: 400
   2023/03/24 13:48:14 882bb8be-31cb-4481-8e28-69b0566a322b: 300
   

   As shown in the output, the code does the following:

   • Drops any existing accounts table.
   • Creates a new accounts table.
   • Inserts some rows into the table.
   • Reads values from the table.
   • Updates values in the table.
   • Deletes values from the table.

What’s next?

Read more about using the Go pgx driver.

You might also be interested in the following pages:

• Client Connection Parameters
• Connection Pooling
• Data Replication
• CockroachDB Resilience
• Replication & Rebalancing