How to select repetitions by SQL query?

Question

SQL

Table with data of site visitors. You need to find out if there are ips that are repeated every day, for example 100.100.100.15

Answer 1

SELECT ip
FROM
(
     SELECT ip, date
     FROM table 
     GROUP BY ip, date
) AS t1
GROUP BY ip
HAVING COUNT(ip) = (SELECT COUNT(date)  FROM table GROUP BY date)

This is a request to select an ip that occurs every day. Or are you interested in ip that are repeated at least once?
Then:

SELECT ip
FROM
(
     SELECT ip, date
     FROM table 
     GROUP BY ip, date
) AS t1
GROUP BY ip
HAVING COUNT(ip) > 1