I’m setting up a database and I’m interested in having a facebook-like friends system. My original plan was to have a table like so:
uid friends 4 30,23,12,33 30 54,92,108 with all these numbers being FK’s to tables with user information. I was told that this is inadvisable and practically impossible since MySQL will only deal with FK’s well if they’re the only placed one in a cell. So maybe something like this?
uid(PK) friend 4 30 4 23 4 12 30 54 30 92 30 108 ect. Won’t this leave me with an enormous number of rows? (tens of thousands?) Is the first technique not worth it in terms of time and efficiency?
10’s of thousands of rows is peanuts, even for Mysql. There is no other way to model a many-to-many relationship. You will have indexes on these ids, which perform better by many orders of magnitude that a substring comparison.