acumular saldos segun quiebre de cuenta

[[oscarac]]

Lo he solucionado momentaneamente asi

Código SQL [-]
 
select Left(Cuenta,2), sum(iif (DH='D', n_imp, 0)) AS Debe, sum(iif (DH='H', n_imp, 0)) AS Haber
from tblmovimientocontable where Periodo = '201001'
group by Left(cuenta,2)
Order by Left(cuenta,2)
union all
select Left(Cuenta,3), sum(iif (DH='D', n_imp, 0)) AS Debe, sum(iif (DH='H', n_imp, 0)) AS Haber
from tblmovimientocontable where Periodo = '201001'
group by Left(cuenta,3)
Union all 
select Left(Cuenta,4), sum(iif (DH='D', n_imp, 0)) AS Debe, sum(iif (DH='H', n_imp, 0)) AS Haber
from tblmovimientocontable where Periodo = '201001'
group by Left(cuenta,4)
Union all
select Cuenta, sum(iif (DH='D', n_imp, 0)) AS Debe, sum(iif (DH='H', n_imp, 0)) AS Haber
from tblmovimientocontable where Periodo = '201001'
group by cuenta

el problema es que los quiebres.... (2,3,4,..) son variables....
entonces....
se me ocurre que podria armar una cadena....