Connect to OceanBase Cloud by using Sequel

This topic describes how to use Sequel to connect to OceanBase Cloud and perform basic operations such as creating tables, inserting data, and querying data.

Prerequisites

• You have installed Ruby and RubyGems.
• You have registered an OceanBase Cloud account and created an instance and a MySQL compatible tenant. For more information, see Create an instance and Create a tenant.

Procedure

1. Check the versions of Ruby and RubyGems.
2. Install the required gem.
3. Obtain the connection information of OceanBase Cloud.
4. Create a sample program.
5. Run the sample program.

Step 1: Check the versions of Ruby and RubyGems

Run the following command in the terminal to check the versions of Ruby and RubyGems:

ruby -v
gem -v

Step 2: Install the required gem

Run the following command to install Sequel and mysql2:

gem install sequel mysql2

Step 3: Obtain the connection information of OceanBase Cloud

1. Log in to the OceanBase Cloud console. In the instance list, expand the information of the target instance, and select Connect > Get Connection String under the target tenant.

   For more information, see Obtain the connection string.

2. Fill in the corresponding information in the URL below based on the created OceanBase Cloud database.

   mysql -h$host -P$port -u$user_name -p$password -D$database_name
   

   Parameter description:

   • $host: the endpoint of the OceanBase Cloud database, for example, t********.********.oceanbase.cloud.
   • $port: the port of the OceanBase Cloud database. The default value is 3306.
   • $database_name: the name of the database to be accessed.
   • $user_name: the account for accessing the database.
   • $password: the password of the account.

Step 4: Create a sample program

1. Create a configuration file named config.rb:

   PASSWORD = ENV['OB_PASSWORD'] || 'your_password'
   
   CLIENT_CONFIG = {
     adapter: 'mysql2',
     host: 'your_host',
     port: your_port,
     username: 'your_username',
     password: PASSWORD,
     all_databases: true
   }
   

2. Create a sample program named main.rb:

   require 'sequel'
   require 'sequel/adapters/mysql2'
   require File.expand_path('config.rb', __dir__)
   
   # Create a connection
   db = Sequel.connect(CLIENT_CONFIG)
   
   # Create a database
   db_name = "ruby_test_db"
   db.run("CREATE DATABASE IF NOT EXISTS #{db_name}")
   
   db.disconnect
   
   # Reconnect to the new database
   CLIENT_CONFIG[:database] = db_name
   db = Sequel.connect(CLIENT_CONFIG)
   puts "Database '#{db_name}' selected"
   
   # Create a table
   db.run("DROP TABLE IF EXISTS users")
   db.run("CREATE TABLE users (
     id INT AUTO_INCREMENT PRIMARY KEY,
     name VARCHAR(255) NOT NULL,
     created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
   )")
   
   # Insert sample data
   sample_names = ["Alice", "Bob", "Charlie", "David"]
   sample_names.each do |name|
     db.run("INSERT INTO users (name) VALUES ('#{name}')")
   end
   
   puts "Table created and sample data inserted successfully"
   puts "Inserted #{sample_names.size} sample records"
   
   # Query and display all data
   results = db[:users]
   puts "\nUsers:"
   results.each do |row|
     puts "ID: #{row[:id]}, Name: #{row[:name]}, Created at: #{row[:created_at]}"
   end
   
   # Close the connection
   db.disconnect
   

Step 5: Run the sample program

1. Run the program:

   ruby main.rb
   

   Expected output:

   Database 'ruby_test_db' selected
   Table created and sample data inserted successfully
   Inserted 4 sample records
   
   Users:
   ID: 1, Name: Alice, Created at: 2025-05-21 15:20:06 +0800
   ID: 2, Name: Bob, Created at: 2025-05-21 15:20:06 +0800
   ID: 3, Name: Charlie, Created at: 2025-05-21 15:20:06 +0800
   ID: 4, Name: David, Created at: 2025-05-21 15:20:06 +0800
   

Common issues

1. Connection error: If you cannot connect to the database, check the following:

   • Whether the database endpoint and port are correct
   • Whether the username and password are correct
   • Whether the network connection is normal

2. Permission error: If you encounter a permission-related error, make sure the user has sufficient permissions to perform the required operations.

3. SQL syntax error: If there is a syntax error in the SQL statement, check whether the SQL statement is correctly written.

Performance optimization suggestions

1. Use Sequel's batch operations.
2. Use a connection pool to manage database connections.
3. Use precompiled queries.
4. Use caching appropriately.
5. Optimize database indexes.