Alter user defined type in SQL Server

Question

I created few user defined types in my database as below

CREATE TYPE [dbo].[StringID] FROM [nvarchar](20) NOT NULL

and assigned them to vario

Answer 1

This is what I normally use, albeit a bit manual:

/* Add a 'temporary' UDDT with the new definition */ 
exec sp_addtype t_myudt_tmp, 'numeric(18,5)', NULL 


/* Build a command to alter all the existing columns - cut and 
** paste the output, then run it */ 
select 'alter table dbo.' + TABLE_NAME + 
       ' alter column ' + COLUMN_NAME + ' t_myudt_tmp' 
from INFORMATION_SCHEMA.COLUMNS 
where DOMAIN_NAME = 't_myudt' 

/* Remove the old UDDT */ 
exec sp_droptype t_mydut


/* Rename the 'temporary' UDDT to the correct name */ 
exec sp_rename 't_myudt_tmp', 't_myudt', 'USERDATATYPE'