Merging rows in MySQL

Question

Suppose I have a table with 4 columns: ID (auto-increment), name, phone and e-mail. The problem is that sometimes the name is repeated. For example:

+----+------+-------+--------------+
| id | name | phone | email        |
+----+------+-------+--------------+
|  1 | aaa  |       |              |
|  2 | aaa  | 123   |              |
|  3 | aaa  |       | aaa@test.com |
+----+------+-------+--------------+

Which would be the best way to merge these 3 entries into one with all the fields present? The expected result would be:

+----+------+-------+--------------+
| id | name | phone | email        |
+----+------+-------+--------------+
|  4 | aaa  | 123   | aaa@test.com |
+----+------+-------+--------------+

Thanks in advance!

Answer 1

You can do this using aggregation, except for the setting of the id . Does this do what you want?

select max(id) + 1, name, max(phone) as phone, max(email) as email
from table t
group by name;

EDIT:

If you wanted to insert a new value and then delete the old ones, you could do:

insert into table(name, phone, email)
    select max(id) + 1, name, max(phone) as phone, max(email) as email
    from table t
    group by name
    having count(*) > 1;

And then:

delete t from table t join
              (select t.name, max(id) as maxid
               from table t
               group by t.name
              ) tt
              on t.name = tt.name and t.id < tt.maxid;