JDBC

It is possible to use JDBC directly from within JRuby. A simple function using the MySQL JDBC driver to perform a SELECT is shown below:

def vegetableFinder(vegetable)
	# This function takes a hashmap of vegetables and attempts to 
	# find them from our grocery database. For each item found, we 
	# call our 'makevegetablesoup' function.

	# Load all required gems
	require "rubygems"
	require "jdbc/mysql"
	require "java"
	
	begin
		# Prep the connection
                Java::com.mysql.jdbc.Driver
		userurl = "jdbc:mysql://HOST/DATABASE"
                connSelect = java.sql.DriverManager.get_connection(userurl, "USERNAME", "PASSWORD")
		stmtSelect = connSelect.create_statement
		
		# Define the query
		selectquery = "SELECT name, type, size, price
					FROM vegetables
					WHERE type = \"#{vegetable["type"]}\" 
					AND size = \"#{vegetable["size"]}\";"

		# Execute the query
		rsS = stmtSelect.execute_query(selectquery)

		# For each row returned do some stuff
		while (rsS.next) do
			veg = Hash.new
			veg["vegname"] = rsS.getObject("name")
			veg["vegtype"] = rsS.getObject("type")
			veg["vegprice"] = rsS.getObject("size")
			veg["vegsize"] = rsS.getObject("price")
			makevegetablesoup(veg)
		end
	end
	# Close off the connection
	stmtSelect.close
        connSelect.close
	return truth
end

INSERTs and UPDATEs are much the same. Again, using the MySQL JDBC driver a simple insert is shown below:

def groceryInsert(vegetable)
	# Inserts a new vegetable type into the grocery database

	# Load all required gems
	require "rubygems"
	require "jdbc/mysql"
	require "java"
	
	begin
		# Prep the connection
                Java::com.mysql.jdbc.Driver
		userurl = "jdbc:mysql://HOST/DATABASE"
		connInsert = java.sql.DriverManager.get_connection(userurl, "USERNAME", "PASSWORD")
		stmtInsert = connInsert.create_statement

		# Do the insert
		rsI = stmtInsert.execute_update("INSERT INTO vegetables										(name,type,size,price)
						VALUES
							   (
							   '#{vegetable["name"]}',
							   '#{vegetable["type"]}',
							   '#{vegetable["size"]}',
							   '#{vegetable["price"]}'
							   );")
		end
	end
	# Close off the connection
	stmtInsert.close
        connInsert.close

	# Return the number of records inserted
	return rsI
end

Remember to have the JDBC driver for your database in your CLASSPATH!