Retrieve user id for users that have 5 specific rows I have 2 tables: Titles and Data
They have a One-to-One relationship
The entry_id in Titles t = entry_id in Data d

I need to retrieve the t.author_id for those users who have 5 specific rows in the Data table.

e.g 

SELECT t.author_id 
FROM titles t, data d
WHERE d.skills = "Skill A"
AND d.skills = "SKILL B"
AND d.skills = "Skill C"
AND d.skills = "Skill D"
AND d.skills = "Skill E"
GROUP BY author_id


I think i have too many joins happening as the query won't finish executing. 

Any ideas?

Thanks.
If your both tables have referential relationship with entry_id then you can fetch your result data through with 'IN' clause. 
No need to write down as many AND operator in the query.

select t.author_id,t.entry_id,d.entry_id

from yourdatabsename.titles as t left outer join yourdatabasename.data  as d

on t.entry_id=d.entry_id

where d.skills IN ('Skill A','Skill B','Skill C','Skill D','Skill E')

Group By t.author_id

Order By t.author_id
;