Solved

mysql alter table to make a column unique

Posted on 2011-09-14
3
495 Views
Last Modified: 2012-05-12
Hi All,

How do I set a column in MySQL as unique?

There maybe duplicates, so they can be deleted.
0
Comment
Question by:detox1978
  • 2
3 Comments
 
LVL 109

Accepted Solution

by:
Ray Paseur earned 500 total points
ID: 36536673
I have never tried to alter a table and add a UNIQUE index to a column that has duplicates.  That would probably fail (I hope).  I think you might want to create a new table with UNIQUE on the column, then INSERT into the new table with a SELECT from the old table, processing the rows one at a time.

MySQL will throw error number #1062 if you attempt to insert duplicate data into a UNIQUE column.  You can trap this error and ignore it if you want to discard the duplicate values.
0
 
LVL 2

Author Comment

by:detox1978
ID: 36536722
thanks for the info.  created a new table, inserted the data, dropped the original and renamed the new.

0
 
LVL 109

Expert Comment

by:Ray Paseur
ID: 36537269
Bingo!  Thanks for the points, ~Ray
0

Featured Post

Efficient way to get backups off site to Azure

This user guide provides instructions on how to deploy and configure both a StoneFly Scale Out NAS Enterprise Cloud Drive virtual machine and Veeam Cloud Connect in the Microsoft Azure Cloud.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Things That Drive Us Nuts Have you noticed the use of the reCaptcha feature at EE and other web sites?  It wants you to read and retype something that looks like this.Insanity!  It's not EE's fault - that's just the way reCaptcha works.  But it is …
Since pre-biblical times, humans have sought ways to keep secrets, and share the secrets selectively.  This article explores the ways PHP can be used to hide and encrypt information.
The viewer will learn how to dynamically set the form action using jQuery.
The viewer will learn how to look for a specific file type in a local or remote server directory using PHP.

776 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question