ALTER TABLE on dependent column

Question

I am trying to alter column datatype of a primary key to tinyint from int.This column is a foreign key in other tables.So,I get the following error:

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Answer 1

If your constraint is on a user type, then don't forget to see if there is a Default Constraint, usually something like DF__TableName__ColumnName__6BAEFA67, if so then you will need to drop the Default Constraint, like this:

ALTER TABLE TableName DROP CONSTRAINT [DF__TableName__ColumnName__6BAEFA67]

For more info see the comments by the brilliant Aaron Bertrand on this answer.