Description
  
   UPDATE changes the values of the columns specified for
   all rows which satisfy condition. Only the columns 
   to be modified need appear as columns in the statement.
  
   Array references use the same syntax found in
   SELECT.
   That is, either single array elements, a range of array
   elements or the entire array may be replaced with a single
   query.
  
   You must have write access to the table in order to modify
   it, as well as read access to any table whose values are
   mentioned in the WHERE condition.
  
  By default UPDATE will update tuples in the table specified 
  and all its sub-tables. If you wish to only update the
  specific table mentioned, you should use the ONLY clause.
  
   Usage
  
   Change word Drama with Dramatic on column kind:
UPDATE films 
SET kind = 'Dramatic' 
WHERE kind = 'Drama';
SELECT * 
FROM films 
WHERE kind = 'Dramatic' OR kind = 'Drama';
 code  |     title     | did | date_prod  |   kind   | len
-------+---------------+-----+------------+----------+-------
 BL101 | The Third Man | 101 | 1949-12-23 | Dramatic | 01:44
 P_302 | Becket        | 103 | 1964-02-03 | Dramatic | 02:28
 M_401 | War and Peace | 104 | 1967-02-12 | Dramatic | 05:57
 T_601 | Yojimbo       | 106 | 1961-06-16 | Dramatic | 01:50
 DA101 | Das Boot      | 110 | 1981-11-11 | Dramatic | 02:29