mysql - Using "not in" on WHERE with AND? -


i'm trying better understanding of how "not in" works in mysql.

for example:

select * current_mailing_list  address1 not in     (select address1 old_mailing_list) ,     city not in (select city old_mailing_list);

in above example, purpose of query list mailing addresses new. address1 street address such 1234 n. main st. problem happens when 1234 n. main st occurs in more 1 city, can happen. decided add city make more unique.

my question is, doing expect do? meaning, should find street addresses (address1) don't exist in old_mailing_list and make sure have different city.

i have done this, address1:

select * current_mailing_list  address1 not in      (select address1 old_mailing_list);

and produced larger list (about 10 times size). wanted add city this. or logic in entirely wrong , need approach?

to use not in, you'll want combine both city , address in same clause mysql supports (other rdbms not support method). others have pointed out, won't desired results using both separately.

try if want use not in:

select *  current_mailing_list  (address1,city) not in      (select address1, city old_mailing_list);

sample sql fiddle demo

i prefer use left join though , check null:

select c.*  current_mailing_list c     left join old_mailing_list o on c.address1 = o.address1 , c.city = o.city o.address1 null

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