Question

I’m using PHP/MySQL and I have to create a new table from an existing one. Here’s the problematic:

Table1:

photo_id   email          name_to   creation_date    link
1          [e-mail]   paul      2012-11-21       link1.com
2          [e-mail]   mark      2012-11-22       link2.com
3          [e-mail]   alex      2012-11-23       link3.com
4          [e-mail]   saul      2012-11-25       link4.com
5          [e-mail]   john      2012-11-26       link5.com
6          [e-mail]   math      2012-11-27       link6.com
7          [e-mail]   fred      2012-11-28       link7.com

In Table1 the email is not unique, it can be repeated several times. Each link is different. With this data, I have to create a new table in which the email is unique with maximum of 3 links if there’s more entries of one email (if so I need the data of the 3 latest entries).

So, in this case, Table2 would be like:

email           link1        creation_date1    name_to1    link2        creation_date2    name_to2    link3        creation_date3    name_to3
[e-mail]    link5.com    2012-11-26        john        link4.com    2012-11-25        saul        link3.com    2012-11-23        alex
[e-mail]    link6.com    2012-11-27        math        link2.com    2012-11-22        mark
[e-mail]    link7.com    2012-11-28        fred 

I know the GROUP_CONCAT feature but it’s not really what I need here since the links would all be in the same column. Is it better to make a SELECT * FROM table1 and process the result into PHP arrays and after that create Table2 or a unique MySQL query would do the trick? Or create multiple MySQL tables?

Table1 is over 10 millions rows.

Any advice would be appreciate.

Thanks.

Answer 1

1) select all unique emails.

2) For each email, take the first 3 rows with that email ordered by creation_date descending.

3) Use that data to insert into new table.

Whatchu think?