Aquí hay una secuencia de comandos que eliminará la columna junto con su restricción predeterminada. Reemplace MYTABLENAME y MYCOLUMNNAME apropiadamente.
declare @constraint_name sysname, @sql nvarchar(max)
select @constraint_name = name
from sys.default_constraints
where parent_object_id = object_id('MYTABLENAME')
AND type = 'D'
AND parent_column_id = (
select column_id
from sys.columns
where object_id = object_id('MYTABLENAME')
and name = 'MYCOLUMNNAME'
)
set @sql = N'alter table MYTABLENAME drop constraint ' + @constraint_name
exec sp_executesql @sql
alter table MYTABLENAME drop column MYCOLUMNNAME
go
