Question

I have the following table structure in my database:

create table Encargado(
ID int primary key,
Nombre varchar(300),
)

create table Area(
ID int primary key,
Nombre varchar(300),
Jefe int foreign key references Encargado(ID)
)

create table Carrera(
ID int primary key,
Nombre varchar(300),
Area int foreign key references Area(ID)
)

create table Formacion(
ID int primary key,
Grado varchar(300),
Lugar varchar(300)
)

create table Docente(
ID int primary key,
Nombre varchar(300),
Carrera int foreign key references Carrera(ID),
Formacion int foreign key references Formacion(ID),
Horario varchar(300)
)

create table Evaluacion(
ID int primary key,
Docente int foreign key references Docente(ID),
Evaluador varchar(300),
Secuencia int,
Pizarra int,
Audiovisual int,
Letra int,
Voz int,
GestosVocabulario int,
Ejemplificacion int,
Respuestas int,
DominioEscenico int,
Participacion int,
Observacion varchar(4000),
Materias varchar(3000),
Valido bit
)

create table Seguimiento(
ID int primary key,
Docente int foreign key references Docente(ID),
Modulo int,
Semestre int,
Ano int,
Fecha datetime,
Hora datetime,
OrdenSecuencia bit,
OrdenSecuenciaObservacion varchar(200),
PortafolioAlumno bit,
PortalofioAlumnoObservacion varchar(200),
AspectosParaEntrevista varchar(3000),
Conclusiones varchar(3000),
Evaluador varchar(300),
DirectorDeArea int foreign key references Encargado(ID),
EncargadoControl int foreign key references Encargado(ID),
)

Say I want to delete an Area, how would I do this? I would need to also delete all Carreras and also all the Docentes.

public void Delete(Area area)
        {
            db.Carreras.DeleteAllOnSubmit(area.Carreras);
            //I'm stuck here. Is this what I should be doing?
        }

Can someone suggest how to handle this?

I’m using C# and Linq-to-SQL. I feel I may have dug myself into a hole by using this table structure or perhaps that’s one of the downfalls of a relational database? :\

Answer 1

I wouldn’t handle this on the Linq-to-SQL side, I’d use cascading deletes on the database side if you truly want to delete all the child records.

For example, with Oracle you can add a “ON DELETE CASCADE” clause to your create table statements, refer to this link.

The cascading delete will handle deleting all the records from the child tables, all with a single delete operation. The beauty of this approach is that no matter where you perform the operation, albeit via Linq-To-SQL, JAVA, ROR, PHP, etc, the logic is centralized in the DB so it works the same way no matter who does the delete.