How to Connect the Ruby to the Postgresql?

Question

I try to connect The ruby to the postgres, but it cannot connecting ,it shows an error "uninitialized constant PGconn".

require "pg"
conn = PGconn.connect("localhost", 5432, "", "", "test1")
res = conn.exec("select * from a;")

Answer 1

The Postgres gem pg is using PG now, PGConn is obsolete. It was still there in pg 0.11.0.

PG.connect example:

require 'pg' 
conn = PG.connect( dbname: 'sales' ) 
conn.exec( "SELECT * FROM pg_stat_activity" ) do |result| 
    result.each do |row| 
        puts row.values_at('procpid', 'usename', 'current_query')
    end
end

PG.connect is a "convenience alias" for PG::Connection.new (related SO post)