[SQL] Relations

  I'm novice in postgresSQL.
  How do you have a relations with two tables?

  Table 1 ->       cod               int 4             index
                   descrition        varchar(30)
                   price             init 4

  Table 2 ->       order             varchar(8)
                   cod               int 4
                   quant             ini 4


  I'm a expected one select with result:


              order  |  descrition | quant | price | total(price * quant)