Connect an application

YSQL
YCQL

The PGX driver is one of the most popular and actively maintained drivers for PostgreSQL. Use the driver to connect to YugabyteDB database to execute DML and DDL statements using the PGX APIs. It also supports the standard database/sql package.

CRUD operations

For Go applications, most drivers provide database connectivity through the standard database/sql API. The following sections break down the example to demonstrate how to perform common tasks required for Go application development using the PGX driver.

To start building your application, make sure you have met the prerequisites.

Step 1: Import the driver package

Import the PGX driver package by adding the following import statement in your Go code.

import (
  "github.com/jackc/pgx/v4"
)

To install the package locally, run the following commands:

mkdir yb-pgx
cd yb-pgx
go mod init hello
go get github.com/jackc/pgx/v4

Step 2: Set up the database connection

Go applications can connect to the YugabyteDB database using the pgx.Connect() function. The pgx package includes all the common functions or structs required for working with YugabyteDB.

Use the pgx.Connect() method to create a connection object for the YugabyteDB database. This can be used to perform DDL and DML operations against the database.

The PGX connection URL is in the following format:

postgresql://username:password@hostname:port/database

Code snippet for connecting to YugabyteDB:

url := fmt.Sprintf("postgres://%s:%s@%s:%d/%s",
                    user, password, host, port, dbname)
conn, err := pgx.Connect(context.Background(), url)

Parameter	Description	Default
user	User connecting to the database	yugabyte
password	User password	yugabyte
host	Hostname of the YugabyteDB instance	localhost
port	Listen port for YSQL	5433
dbname	Database name	yugabyte

Use SSL

For a YugabyteDB Aeon cluster, or a YugabyteDB cluster with SSL/TLS enabled, set the SSL-related environment variables as below at the client side. SSL/TLS is enabled by default for client-side authentication. Refer to Configure SSL/TLS for the default and supported modes.

$ export PGSSLMODE=verify-ca
$ export PGSSLROOTCERT=~/root.crt  # CA certificate file is downloaded as `root.crt` under home directory. Modify your path accordingly.

Environment variable	Description
PGSSLMODE	SSL mode used for the connection
PGSSLROOTCERT	Path to the root certificate on your computer

Step 3: Write your application

Create a file called QuickStartApp.go and add the following contents into it:

package main

import (
  "context"
  "fmt"
  "log"
  "os"

  "github.com/jackc/pgx/v4"
)

const (
  host     = "127.0.0.1"
  port     = 5433
  user     = "yugabyte"
  password = "yugabyte"
  dbname   = "yugabyte"
)

func main() {
    // SSL/TLS config is read from env variables PGSSLMODE and PGSSLROOTCERT, if provided.
    url := fmt.Sprintf("postgres://%s:%s@%s:%d/%s",
                       user, password, host, port, dbname)
    conn, err := pgx.Connect(context.Background(), url)
    if err != nil {
        fmt.Fprintf(os.Stderr, "Unable to connect to database: %v\n", err)
        os.Exit(1)
    }
    defer conn.Close(context.Background())

    var dropStmt = `DROP TABLE IF EXISTS employee`;

    _, err = conn.Exec(context.Background(), dropStmt)
    if err != nil {
        fmt.Fprintf(os.Stderr, "Exec for drop table failed: %v\n", err)
    }
    // The `conn.Exec()` function also returns an `error` object which,
    // if not `nil`, needs to be handled in your code.
    var createStmt = `CREATE TABLE employee (id int PRIMARY KEY,
                                             name varchar,
                                             age int,
                                             language varchar)`;
    _, err = conn.Exec(context.Background(), createStmt)
    if err != nil {
        fmt.Fprintf(os.Stderr, "Exec for create table failed: %v\n", err)
    }
    fmt.Println("Created table employee")

    // Insert data using the conn.Exec() function.
    var insertStmt string = "INSERT INTO employee(id, name, age, language)" +
        " VALUES (1, 'John', 35, 'Go')";
    _, err = conn.Exec(context.Background(), insertStmt)
    if err != nil {
        fmt.Fprintf(os.Stderr, "Exec for create table failed: %v\n", err)
    }
    fmt.Printf("Inserted data: %s\n", insertStmt)
    // The pgx driver automatically prepares and caches statements by default, so you don't have to.

    // Query data using the conn.Query() function with the SELECT statements.
    var name string
    var age int
    var language string
    rows, err := conn.Query(context.Background(), "SELECT name, age, language FROM employee WHERE id = 1")
    if err != nil {
        log.Fatal(err)
    }
    defer rows.Close()
    fmt.Printf("Query for id=1 returned: ");
    // Results are returned in pgx.Rows which can be iterated using the pgx.Rows.next() method.
    for rows.Next() {
        // Read the data using pgx.rows.Scan().
        err := rows.Scan(&name, &age, &language)
        if err != nil {
           log.Fatal(err)
        }
        fmt.Printf("Row[%s, %d, %s]\n", name, age, language)
    }
    err = rows.Err()
    if err != nil {
        log.Fatal(err)
    }
}

The const values are set to the defaults for a local installation of YugabyteDB. If you are using YugabyteDB Aeon, replace the const values in the file as follows:

host - The host address of your cluster. The host address is displayed on the cluster Settings tab.
user - Your YugabyteDB database username. In YugabyteDB Aeon, the default user is admin.
password - Your YugabyteDB database password.
dbname - The name of the YugabyteDB database. The default name is yugabyte.
port is set to 5433, which is the default port for the YSQL API.

Run the project QuickStartApp.go using the following command:

go run QuickStartApp.go

You should see output similar to the following:

Created table employee
Inserted data: INSERT INTO employee(id, name, age, language) VALUES (1, 'John', 35, 'Go')
Query for id=1 returned: Row[John, 35, Go]