ALTER TABLE CITIES
ADD COLUMN REGION;

ALTER TABLE NEIGHBORHOOD
ADD PRIMARY KEY (ID_CITY, NEIGHBORHOOD); 

CREATE TABLE STREETS(
    ID_STREET INTEGER(5), 
    NM_STREET CHAR (50), 
    ID_CITY INTEGER(5), 
    ID_NEIGHBORHOOD INTEGER(5), 
    OBS CHAR (50)
);

CREATE INDEX ON STREETS (ID_NEIGHBORHOOD);

ALTER TABLE STREETS
DROP COLUMN OBS;