Generate SQL to update primary key

Question

I want to change a primary key and all table rows which reference to this value.

# table master
master_id|name
===============
foo|bar

# table detail
detail         


        

Answer 1

The easiest way to deal with primary key changes - by far - is to ALTER your referring foreign key constraints to be ON UPDATE CASCADE.

You are then free to update the primary key values, and the changes will cascade to child tables. It can be a very slow process due to all the random I/O, but it will work.

You do need to watch out not to violate uniqueness constraints on the primary key column during the process.

A fiddlier but faster way is to add a new UNIQUE column for the new PK, populate it, add new columns to all the referring tables that point to the new PK, drop the old FK constraints and columns, then finally drop the old PK.