Alter user defined type in SQL Server

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I created few user defined types in my database as below

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

and assigned them to various tables. The tables in my database are in various schemas (not only dbo)

But I realized I need bigger field, and I need to alter, e.g increase from [nvarchar](20) to [nvarchar](50), but there is no ALTER TYPE statement.

I need a script that uses a temp table/cursor whatever and saves all the tables and fields where my type is used. Then change existing fields to base type - e.g. from CustID [StringID] to CustID [nvarchar(20)]. Drop the user type and recreate it with new type - e.g. nvarchar(50) and finally set back fields to user type

I do not have rules defined on types, so don't have to drop rules and re-add them.

Any help is appreciated.

tsql sql-server sql
10 Answers

I ran into this issue with custom types in stored procedures, and solved it with the script below. I didn't fully understand the scripts above, and I follow the rule of "if you don't know what it does, don't do it".

In a nutshell, I rename the old type, and create a new one with the original type name. Then, I tell SQL Server to refresh its details about each stored procedure using the custom type. You have to do this, as everything is still "compiled" with reference to the old type, even with the rename. In this case, the type I needed to change was "PrizeType". I hope this helps. I'm looking for feedback, too, so I learn :)

Note that you may need to go to Programmability > Types > [Appropriate User Type] and delete the object. I found that DROP TYPE doesn't appear to always drop the type even after using the statement.

/* Rename the UDDT you want to replace to another name */ 
exec sp_rename 'PrizeType', 'PrizeTypeOld', 'USERDATATYPE';

/* Add the updated UDDT with the new definition */ 
CREATE TYPE [dbo].[PrizeType] AS TABLE(
    [Type] [nvarchar](50) NOT NULL,
    [Description] [nvarchar](max) NOT NULL,
    [ImageUrl] [varchar](max) NULL
);

/* We need to force stored procedures to refresh with the new type... let's take care of that. */
/* Get a cursor over a list of all the stored procedures that may use this and refresh them */
declare sprocs cursor
  local static read_only forward_only
for
    select specific_name from information_schema.routines where routine_type = 'PROCEDURE'

declare @sprocName varchar(max)

open sprocs
fetch next from sprocs into @sprocName
while @@fetch_status = 0
begin
    print 'Updating ' + @sprocName;
    exec sp_refreshsqlmodule @sprocName
    fetch next from sprocs into @sprocName
end
close sprocs
deallocate sprocs

/* Drop the old type, now that everything's been re-assigned; must do this last */
drop type PrizeTypeOld;
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