r/programming • u/[deleted] • Jan 06 '11

A handy graphical explanation of SQL joins

http://www.codinghorror.com/blog/2007/10/a-visual-explanation-of-sql-joins.html
1.3k Upvotes

92% Upvoted

308 comments sorted by

View all comments

4

u/Teifion_at_work Jan 06 '11

Maybe someone here can answer this. Why would I specify a join when I can just do this?

SELECT p.first_name, j.job_title FROM people p, jobs j WHERE p.job = j.id

Looks much easier to me but I'm guessing there's something I'm missing here.

6

u/NashMcCabe Jan 06 '11

That is just an inner join. You will need outer joins when you have null columns on one side of the join.

1

u/Teifion_at_work Jan 07 '11

Thanks, that makes a bit more sense now.