The result of join is always a string, but the object to be joined can be of many types (generators, list, tuples, etc). .join is faster because it allocates memory only once. Better than classical concatenation (see, extended explanation). Once you learn it, it's very comfortable and you can do tricks like this to add parentheses.
How to perform a LEFT JOIN in SQL Server between two SELECT statements ...
SELECT WeddingTable, TableSeat, TableSeatID, Name, Two.Meal FROM table1 as One INNER JOIN table2 as Two ON One.WeddingTable = Two.WeddingTable AND One.TableSeat = Two.TableSeat I only get one of the criteria 1/criteria 2 combinations even when I know for a fact that there are 3 or 4. How do I get all combinations? Take the situation where there is a wedding where table1 is basically a seating ...
sql - How to do join on multiple criteria, returning all combinations ...
How to concatenate (join) items in a list to a single string