something tells me that the rows between these two tables (using table names like table1, table2 doesn't provide useful context) are not related to each other using any sort of foreign key, but are two different types of data (that perhaps should all be in one table) that the OP wants to retrieve with the data for each username (which should actually be a userid) together in the result set. if so, you need to use a UNION query.
yeah. u are right. the only relationship with both tables is the username. a table may have more info on it than the other.