## Prerequisites
Install the Ruby PostgreSQL driver (`pg` gem) using the following command:
```sh
$ gem install pg -- --with-pg-config=/postgres/bin/pg_config
```
For more information on the driver, see the [pg driver documentation](https://deveiate.org/code/pg/).
## Create the application
Create a file `yb-sql-helloworld.rb` and add the following content to it.
```python
#!/usr/bin/env ruby
require 'pg'
begin
# Output a table of current connections to the DB
conn = PG.connect(host: '127.0.0.1', port: '5433', dbname: 'yugabyte', user: 'yugabyte', password: 'yugabyte')
# Create table
conn.exec ("CREATE TABLE employee (id int PRIMARY KEY, \
name varchar, age int, \
language varchar)");
puts "Created table employee\n";
# Insert a row
conn.exec ("INSERT INTO employee (id, name, age, language) \
VALUES (1, 'John', 35, 'Ruby')");
puts "Inserted data (1, 'John', 35, 'Ruby')\n";
# Query the row
rs = conn.exec ("SELECT name, age, language FROM employee WHERE id = 1");
rs.each do |row|
puts "Query returned: %s %s %s" % [ row['name'], row['age'], row['language'] ]
end
rescue PG::Error => e
puts e.message
ensure
rs.clear if rs
conn.close if conn
end
```
## Run the application
To use the application, run the following command:
```sh
$ ./yb-sql-helloworld.rb
```
You should see the following output.
```output
Created table employee
Inserted data (1, 'John', 35, 'Ruby')
Query returned: John 35 Ruby
```
## Learn more
- Build Ruby applications using [YugabyteDB Ruby Driver for YCQL](../ycql/)
- Build Ruby applications using [Active Record ORM](../activerecord/)