Anand Buddhdev <[EMAIL PROTECTED]> wrote: > > I'm using mysql version 3.23.58, on Fedora core 1 (the default > supplied on the system). > > I have searched the mailing list archives, and google, for my query, > but have not yet found an answer. > > Does anyone know if it's possible to define 2 columns in a table, with > a constraint that will ensure that values on both columns are unique? > For example, if I have columns "a" and "b", then if I insert value "x" > in column a, then I may not insert value "x" again in EITHER column > "a" or column "b" again. > > I'm trying to develop a structure for a table that will hold a user's > primary email address, and an alias, and I'd like to have a column > called "address" and a column called "alias", and of course, there > must be no address or alias duplication. This allows addition and > removal of an address and its alias in one insert, and if the insert > fails, then we know there's duplication, and return an error message. > > I have thought of other ways around this issue, but my ideal solution > would be as above. If this is not possible, then I will go back to my > other (IMHO less elegant) solutions.
No, you can't do in the above way. You can first check with SELECT statement if address or alias already exists. -- For technical support contracts, goto https://order.mysql.com/?ref=ensita This email is sponsored by Ensita.net http://www.ensita.net/ __ ___ ___ ____ __ / |/ /_ __/ __/ __ \/ / Egor Egorov / /|_/ / // /\ \/ /_/ / /__ [EMAIL PROTECTED] /_/ /_/\_, /___/\___\_\___/ MySQL AB / Ensita.net <___/ www.mysql.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
