Question

SELECT DISTINCT addresses.email FROM addresses 
WHERE addresses.user_id IN (SELECT  user_group.id_user_groups FROM user_group
WHERE id_group_groups IN (SELECT news_group.groupid_newsg FROM news_group 
WHERE newsid_news_good=1))

The above mentioned SQL query is not executing! It gets hanged until I stop the query. I have tried SQL operator “UNION” after first SELECT statement, but it displays all the email addresses which does not belong to a group. I want to select only those email addresses of the users who belong to “id_group_groups =5” (pls see the query below ) and are subscribed to “newsid_news_good=1”.

The following query runs perfectly fine:

SELECT DISTINCT addresses.email FROM addresses 
WHERE addresses.user_id IN (SELECT user_group.id_user_groups FROM user_group 
WHERE id_group_groups =5 )

Does anybody have an idea what is the problem with the first query? Help will be strongly appreciated!

Answer 1

I think the sub selects complicate your problem. If I understand it right, it would be easier to solver your problem using joins instead of sub selects.

Try out something like this:

SELECT DISTINCT addresses.email
FROM addresses
JOIN user_group
    ON user_group.id_user_groups = adresses.USER_ID
JOIN news_group
    ON news_group.groupid_newsg = user_group.id_group_groups
WHERE newsid_news_good = 1