Re: Remove duplicated entries (between 2 columns)

[timb]

You can use UNION syntax to return only distinct e-mail addresses. See http://dev.mysql.com/doc/mysql/en/union.html for more information. However this won't work if you need other info such as customer name or a primary key that could be used to run an update query.

I think you would need another query to select duplicates and then update the fields, but not sure you should do that. What happens if Mary and John have the same e-mail so you delete John's e-mail address but then Mary changes her e-mail address? This leaves you with no way to contact John.

I recommend that you use a query to select distinct e-mail addresses and leave the data as it is.