should i use insert select or just loop through with insert ?

Question

i have extracted a list of usernames using the answers from this:

http://stackoverflow.com/questions/1273259/how-to-optimize-mysql-query-if-i-have-too-many-or-operators-in-my-query

now i have another issue. I have a friend table made up of just 2 columns, requestor and buddy both form a composite primary key.

Now suppose i have an array of facebook friends for a given user using the above SO question.

how do i automatically make them friends in my web app as well?

That means if i have 5 actual friends for a user called 'usera'. i need to perform 10 insert statements.

eg: friendA, usera and usera, friendA so that friendA is reflected as a friend for usera.

i understand that insert select is efficient. but unfortunately the list of usernames of these friends are obtained via a PHP array of values using IN clause as suggested by fellow SO members in my above question.

So what should i do?

should i

a) loop through the names and perform 2 insert statements for each step?

b) use insert select? but how to do it exactly?

my DB is designed this way:

1 table called users with usernames and fb_uid where the username is primary key and fb_uid is nullable.

1 table called friends with a column called requestor and another column called buddy. Both columns form a composite key.

A friendship is established between 2 people (usera, userb) in my web app when you have the following data: (usera, userb) and (userb, usera) in the friends table.

Thank you.

Answer 1

You can always make bulk insert.

INSERT INTO friends (user_id, friend_user_id) VALUES (1, 2), (2, 1)

Answer 2

I would go with INSERT SELECT's, you can find the detailed syntax here.