MySQL query help moving data between tables

Question

I've imported by phpbb3 forum in bbpress using the built-in importer. All of the anonymous users from bbpress who didn't have accounts, but were allowed to post are disconnected from there posts and everything is showing up as anonymous in bbpress. I grabbed all the post_usernames from phpbb_posts and created users with this query:

INSERT INTO wp_users (user_login)
    SELECT DISTINCT post_username 
    FROM phpbb_posts

Now I'm trying to do a query between the 3 different tables. Something along these lines:

SELECT ID FROM wp_users 
INSERT INTO wp_posts(post_author)
WHERE wp_posts(post_date) = phpbb_posts(post_time)
  AND phpbb_posts(post_username) = wp_users(user_login)

Obviously this isn't right... probably syntax errors, but I also need to add some way of telling MySQL that the user_login has to be attached to the ID from the first line. Hopefully this makes sense. Thanks in advance for any help!

Updated queries:

SELECT ID FROM wp_users

SELECT post_time FROM phpbb_posts = post_date
SELECT post_username FROM phpbb_posts = user_login

hopefully this syntax makes more sense. These did work and they select the right information. The problem is I don't know how to write the WHERE statement properly and like you said baskint, I think I need to make the last statement a sub-query somehow. Thanks again!

Answer 1

I am still not sure what are the PK's (Primary Key) and FK's (Foreign Key) relationships of each table. However, assuming that wp_users is the primary table and phpbb_posts.post_username is the FK of wp_users.user_login...:

SELECT `wp_users`.`ID` 
FROM `wp_users` INNER JOIN
(SELECT `phpbb_posts`.`post_username` FROM `phpbb_posts`, `wp_posts` WHERE `phpbb_posts`.`post_time` = `wp_posts`.`post_date` ) AS `posts`
ON `wp_users`.`user_login` = `posts`.`post_username`;

EDIT (Dec-05-2012): After chatting and going through specific, @sbroways had to change data-types on some fields and a few other modifications. In turn, the final query turned out to be:

SELECT wp_users.*, ws_posts.*
FROM wp_users INNER JOIN ws_posts
ON wp_users.user_login = ws_posts.user_login

Answer 2

you're right. your syntax is confusing and not correct. trying to understand what you are trying to accomplish. in second query, why are you selecting and inserting at the same time? perhaps i am missing something, but can you state what you are trying to pull out from which tables and how you would like to see the results in plain English?

Also you can think in terms of sub-queries (SELECT * FROM b WHERE id IS IN (SELECT Id from a). You can cascade this a few times and perhaps get to your answer.