how to check mysql connexion

I would want to check if there is a connexion with the database before execute the query . But if i write the if mysql_connection ... it passes twice on mysql_connection.

def mysql_connection puts "mysql_connection 1"

         read_config_file
        @connexion = Mysql2::Client.new(:host => @conf['host'], :username => @conf['user'], :password => @conf['password'], :database=> @conf['base'], :port => @conf['port'])
 end 

######################
#                    #
#  USER QUERY MYSQL  #
######################

 def mysql_select_user(value)
        puts "select"

#         if mysql_connection then
           p = mysql_connection.query("select #{value} from User")   
                p.each do |f| 
                 puts "value : #{f}" 
                 mysql_close
                end 
#       else
#      end 
 end