La respuesta de James funciona bien si conoce el nombre de la restricción real. Lo complicado es que en el legado y otros escenarios del mundo real, es posible que no sepas cómo se llama la restricción.
Si este es el caso, corre el riesgo de crear restricciones duplicadas, para evitar puede usar:
create function fnGetForeignKeyName
(
@ParentTableName nvarchar(255),
@ParentColumnName nvarchar(255),
@ReferencedTableName nvarchar(255),
@ReferencedColumnName nvarchar(255)
)
returns nvarchar(255)
as
begin
declare @name nvarchar(255)
select @name = fk.name from sys.foreign_key_columns fc
join sys.columns pc on pc.column_id = parent_column_id and parent_object_id = pc.object_id
join sys.columns rc on rc.column_id = referenced_column_id and referenced_object_id = rc.object_id
join sys.objects po on po.object_id = pc.object_id
join sys.objects ro on ro.object_id = rc.object_id
join sys.foreign_keys fk on fk.object_id = fc.constraint_object_id
where
po.object_id = object_id(@ParentTableName) and
ro.object_id = object_id(@ReferencedTableName) and
pc.name = @ParentColumnName and
rc.name = @ReferencedColumnName
return @name
end
go
declare @name nvarchar(255)
declare @sql nvarchar(4000)
-- hunt for the constraint name on 'Badges.BadgeReasonTypeId' table refs the 'BadgeReasonTypes.Id'
select @name = dbo.fnGetForeignKeyName('dbo.Badges', 'BadgeReasonTypeId', 'dbo.BadgeReasonTypes', 'Id')
-- if we find it, the name will not be null
if @name is not null
begin
set @sql = 'alter table Badges drop constraint ' + replace(@name,']', ']]')
exec (@sql)
end
constraint_object_id
lugar de soloobject_id