store two tables into a single table in mySQL
If you want to stream changes from tempA and tempA1 to temp, you can use trigger to do this
create trigger for both tables

Example: 

DELIMITER $$ 
CREATE TRIGGER `insert_to_temp` AFTER INSERT
ON `tempa`
FOR EACH ROW BEGIN
    if new.txt1 is not null THEN
        insert into temp values(new.txt1);
 END IF;
END$$ 
DELIMITER ;


And do this for tempa1

but if you want to do a batch insert you can run:

insert into temp select * from tempa where txt1 is not null union select * from tempa1 where txt2 is not null