merging two records in a relational table -advice?

[sfullman]

I have a master table with field UserName. All other tables in the system (that deal with order information, etc.) reference this field as a foreign key. If I delete that user I'll delete their records, except for the fact that I have ON DELETE RESTRICT in place. Life is good.

Now, suppose I have JSmith01 and JSmith02 in the system and want to merge his record (it's a duplicate). I'm thinking I can:

1. suspend the UNIQUE key constraint in the master table for that field UserName.
2. UPDATE mastertable SET UserName='JSmith01' WHERE UserName='JSmith02'
3. This would cascade the new UserName value to all of JSmith02's orders
4. Get the best of JSmith02's information (if present), update JSmith01's to reflect, then delete JSmith02
5. Now, reactivate the UNIQUE key constraint on the field.

Any thoughts on this? Main area I'm interested in knowing about is suspending a reference or overriding it temporarily.

thanks,
Sam

[bastien]

http://dev.mysql.com/doc/mysql/en/innodb-foreign-key-constraints.html

[Sxooter]

Sounds like you're going about it the long way. Why not just change the sub table's key:

update subtable set fkfield='johnsmith1' where fgkfield='johnsmith2';