mysql select where values are repeated - mysql

Question

My table is similar to the one below. I would like to select records where city and town matches and code or area has repetition. In this case rows the result should be all rows except the ones with id 3 and 5. Thanks for looking at this
city town id code1 code2 code3 code4 area1 area2 area3 area4
----------------------------------------------------------------------------------
dublin town1 1 1 2 3 5 1 2 3 4
dublin town1 2 2 8 10 6 7 8 9
dublin town1 3 12 13 15 11 12 13 14
dublin town2 4 1 2 3 5 1 2 3 4
dublin town2 5 6 7 8 10 6 7 8 9
dublin town2 6 11 12 13 15 1 12 13 14
http://sqlfiddle.com/#!2/0bbe7/1/0

Answer 1

Using INNER JOIN,
select a.*
from bigcities a inner join bigcities b
on a.city = b.city
and a.town = b.town
and a.id != b.id
and (a.code1 = b.code1
or a.code2 = b.code2
or a.code3 = b.code3
or a.code4 = b.code4
or a.area1 = b.area1
or a.area2 = b.area2
or a.area3 = b.area3
or a.area4 = b.area4
);
Demo.

Answer 2

This is pretty much what the exists clause can do. Here is a solution for your conditions:
select t.*
from <table> t
where exists (select 1
from <table> t2
where t2.city = t.city and
t2.town = t.town and
t2.id <> t.id and
(t2.code1 = t.code1 or t2.code2 = t.code2 or t2.code3 = t.code3 or t2.code4 = t.code4 or
t2.area1 = t.area1 or t2.area2 = t.area2 or t2.area3 = t.area3 or t2.area4 = t.area4
)

Answer 3

You can do it with the following query
--We do a query to the table to get the rows and then we do a subquery
--to get all the rows with the same criteria. We know it is repeated
--because the counter of rows > 1.
--If you want to get only where it is repeated 2 o 3, etc, you only need to change
--the COUNT() > 1
SELECT *
FROM tableName t
WHERE (
SELECT COUNT(*) FROM tableName tRep WHERE
t.city = tRep.city AND
t.town = tRep.town AND
((t.code1 = tRep.code1 AND t.code2 = tRep.code2 AND t.code3 = tRep.code3 AND t.code4 = tRep.code4) OR
(t.area1 = tRep.area1 AND t.area2 = tRep.area2 AND t.area3 = tRep.area3 AND t.area4 = tRep.area4))
) > 1