InnoDB, Writing TRIGGER to INSERT into tables
Given your table structure:

create table user_address (
u_id integer auto_increment primary key,
street_name varchar(1000),
locality_name varchar(1000)
);

create table street_master
(
s_id integer auto_increment primary key,
s_name varchar(1000)
);


This will do the job:

DELIMITER $$
create trigger user_address_btrig
before insert on user_address
for each row
begin
DECLARE CNT INT;
SET CNT = ( select count(*) from street_master where s_name = new.street_name );

IF CNT=0
THEN
insert into street_master (s_name) values (NEW.street_name);
END IF;
end;
$$
DELIMITER ;


To test:

insert into user_address (street_name, locality_name) values ( 'test street', 'test locality' );

select * from street_master where s_name = 'test street';


I suggest you read the MySQL documentation on triggers and learn for yourself.