PHP / MySQL有SELECT…INSERT和/或SELECT…INSERT…DELETE

Question

I'm new to MySQL, and I'm trying to do the following and hoping I can do it all with a single PHP query to MySQL call rather than having to call, store in php, call, store in php etc.

Here's my database setup. 1. table of users, including email address. 2. table of 'invitees' by email address and user who invited the invitee 3. table of 'friends'

I want to join the table of users with the table of invitees to determine which invitees have registered as users and who invited them (keeping in mind they might have been invited by more than 1 person). From there I'll insert the newly registered invitee along with the person who invited him into the friends table. Finally I will delete that invitee from the invited table so that he won't keep receiving invitations.

I see how to do this with 3 separate php calls to mysql: 1. a JOIN to find the users who are in the user table and the invitee table (the join will also identify who invited them) 2. an INSERT to put the pair into the friends table 3. a DELETE to remove the user from the invitee list.

But this will be higher traffic/less optimized with multiple calls to the MySQL server and also a lot of data stored by my php script that I really just need for the next MySQL call. I have a feeling this should be possible in just 1 call with no data returned to the php script.

I see there is an INSERT...SELECT MySQL call ( http://dev.mysql.com/doc/refman/5.0/en/insert-select.html ), but I have not been able to find a way to combine steps 1 and 2 above, which would be a SELECT...INSERT option. Does this exist? I tried the following, but it didn't work...something like this would be my ideal.

SELECT users.user as user1, invited2.user as user2, invited2.email as email2 FROM users RIGHT JOIN invited2 ON users.email=invited2.invitee; 
INSERT INTO friends (user, friend) VALUES (user1, user2), (user2, user1);  
DELETE FROM invited2 WHERE invited2.email = email2; 

The part before INSERT INTO works on its own, but like I said, if I just return that to my php script, I'll just have to store all the results and then call the second myself. Is there a way to do this in one call? And if so, is there a way to also tack on a delete statement (DELETE from invited2 WHERE invitee=users.email) afterwards?

Any advice would be appreciated. Thanks in advance.

Answer 1

MySQL does provide a INSERT...SELECT ( http://dev.mysql.com/doc/refman/5.1/en/insert-select.html )

Your SQL can be edited to:

INSERT INTO friends (user, friend)
SELECT users.user as user1, invited2.user as user2
FROM users
RIGHT JOIN invited2 ON users.email=invited2.invitee;

DELETE invited2
FROM users
RIGHT JOIN invited2 ON users.email=invited2.invitee;

In this case, INNER JOIN seems to make more sense than RIGHT JOIN.