si se puede, seria algo asi:
Código SQL:
Ver originalSELECT * FROM
FROM comprobantes comp
LEFT JOIN clientes clie ON clie.id=comp.idcliente
LEFT JOIN (
SELECT clie.idcliente, COUNT(clie.razonsoc) AS total
FROM comprobantes comp
LEFT JOIN clientes clie ON clie.id=comp.idcliente
WHERE comp.fecha>='2015/01/01' AND comp.fecha<='2015/01/31' AND comp.condicion='EFT' OR comp.condicion='CTA'
GROUP BY clie.idcliente
) AS t1 ON (t1.idcliente=clientes.idcliente)
WHERE comp.fecha>='2015/01/01' AND comp.fecha<='2015/01/31' AND comp.condicion='EFT' OR comp.condicion='CTA'