Hello MySQL Gurus -
I have 3 tables:
all_customers, opt_out_customers, and opt_in_customers
Let's say there's an id column and an email_address column in each.
I'm sending a newsletter - I want to send it to:
all_customers except where opt_out or opt_in
opt_in except where in all_customers (so as not to send it twice)
I have to use MySQL 4.0. (no sub-selects, etc.)
I had previously tried with a 'LEFT JOIN' but it only seemed to work to
exclude one or the other (e.g. where NULL). Might a 'UNION' work here?
Thanks for any info / examples.
s7
